diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c6b9df0..5cf92080 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -133,7 +133,7 @@ if(UNIX)
     target_compile_options(sfizz PRIVATE -fno-rtti -fno-exceptions)
     target_link_libraries(sfizz stdc++fs)
 endif(UNIX)
-target_link_libraries(sfizz absl::strings sndfile absl::flat_hash_map readerwriterqueue absl::flags_parse)
+target_link_libraries(sfizz jack absl::strings sndfile absl::flat_hash_map readerwriterqueue absl::flags_parse)
 
 ###############################
 # Test application
diff --git a/sources/Globals.h b/sources/Globals.h
index 4bd0768c..f3d54bf6 100644
--- a/sources/Globals.h
+++ b/sources/Globals.h
@@ -7,7 +7,7 @@ namespace config
 {
     constexpr double defaultSampleRate { 48000 };
     constexpr int defaultSamplesPerBlock { 1024 };
-    constexpr int preloadSize { 32768 };
+    constexpr int preloadSize { 8192 };
     constexpr int numChannels { 2 };
     constexpr int numVoices { 64 };
     constexpr int numLoadingThreads { 4 };
diff --git a/sources/Main.cpp b/sources/Main.cpp
index b512dfe4..7f99893c 100644
--- a/sources/Main.cpp
+++ b/sources/Main.cpp
@@ -1,21 +1,152 @@
+#include "StereoSpan.h"
 #include "Synth.h"
-#include <iostream>
 #include <absl/flags/parse.h>
 #include <absl/types/span.h>
+#include <atomic>
+#include <bits/stdint-uintn.h>
+#include <cstddef>
+#include <ios>
+#include <iostream>
+#include <jack/jack.h>
+#include <jack/midiport.h>
+#include <jack/types.h>
+#include <ostream>
+#include <signal.h>
+#include <string_view>
+#include <thread>
+using namespace std::literals;
+
+static jack_port_t* midiInputPort;
+static jack_port_t* outputPort1;
+static jack_port_t* outputPort2;
+static jack_client_t* client;
+
+namespace midi {
+constexpr uint8_t statusMask { 0b11110000 };
+constexpr uint8_t channelMask { 0b00001111 };
+constexpr uint8_t noteOff { 0x80 };
+constexpr uint8_t noteOn { 0x90 };
+constexpr uint8_t polyphonicPressure { 0xA0 };
+constexpr uint8_t controlChange { 0xB0 };
+constexpr uint8_t programChange { 0xC0 };
+constexpr uint8_t channelPressure { 0xD0 };
+constexpr uint8_t pitchBend { 0xE0 };
+constexpr uint8_t systemMessage { 0xF0 };
+
+constexpr uint8_t status(uint8_t midiStatusByte)
+{
+    return midiStatusByte & statusMask;
+}
+constexpr uint8_t channel(uint8_t midiStatusByte)
+{
+    return midiStatusByte & channelMask;
+}
+}
+
+static std::atomic<bool> keepRunning [[maybe_unused]] { true };
+
+int process(jack_nframes_t numFrames, void* arg [[maybe_unused]])
+{
+    auto synth = reinterpret_cast<sfz::Synth*>(arg);
+
+    auto buffer = jack_port_get_buffer(midiInputPort, numFrames);
+    assert(buffer);
+
+    auto numMidiEvents = jack_midi_get_event_count(buffer);
+    jack_midi_event_t event;
+
+    for (uint32_t i = 0; i < numMidiEvents; ++i) {
+        if (jack_midi_event_get(&event, buffer, i) != 0)
+            continue;
+
+        if (event.size == 0)
+            continue;
+
+        switch (midi::status(event.buffer[0])) {
+        case midi::noteOff:
+            DBG("[MIDI] Note " << event.buffer[1] << " OFF at time " << event.time);
+            synth->noteOff(event.time, midi::channel(event.buffer[0]), event.buffer[1], event.buffer[2]);
+            break;
+        case midi::noteOn:
+            DBG("[MIDI] Note " << event.buffer[1] << " ON at time " << event.time);
+            synth->noteOn(event.time, midi::channel(event.buffer[0]), event.buffer[1], event.buffer[2]);
+            break;
+        case midi::polyphonicPressure:
+            DBG("[MIDI] Polyphonic pressure on at time " << event.time);
+            break;
+        case midi::controlChange:
+            DBG("[MIDI] CC " << event.buffer[1] << " at time " << event.time);
+            synth->cc(event.time, midi::channel(event.buffer[0]), event.buffer[1], event.buffer[2]);
+            break;
+        case midi::programChange:
+            DBG("[MIDI] Program change at time " << event.time);
+            break;
+        case midi::channelPressure:
+            DBG("[MIDI] Channel pressure at time " << event.time);
+            break;
+        case midi::pitchBend:
+            DBG("[MIDI] Pitch bend at time " << event.time);
+            break;
+        case midi::systemMessage:
+            DBG("[MIDI] System message at time " << event.time);
+            break;
+        }
+    }
+
+    StereoSpan<float> output {
+        jack_port_get_buffer(outputPort1, numFrames),
+        jack_port_get_buffer(outputPort2, numFrames), 
+        numFrames
+    };
+
+    synth->renderBlock(output);
+
+    return 0;
+}
+
+int sampleBlockChanged(jack_nframes_t nframes, void* arg [[maybe_unused]])
+{
+    if (arg == nullptr)
+        return 0;
+
+    auto synth = reinterpret_cast<sfz::Synth*>(arg);
+    DBG("Sample per block changed to " << nframes);
+    synth->setSamplesPerBlock(nframes);
+    return 0;
+}
+
+int sampleRateChanged(jack_nframes_t nframes, void* arg [[maybe_unused]])
+{
+    if (arg == nullptr)
+        return 0;
+
+    auto synth = reinterpret_cast<sfz::Synth*>(arg);
+    DBG("Sample rate changed to " << nframes);
+    synth->setSampleRate(nframes);
+    return 0;
+}
+
+static void done(int sig [[maybe_unused]])
+{
+    std::cout << "Closing..." << '\n';
+    if (client != nullptr)
+        jack_client_close(client);
+    exit(0);
+}
 
 int main(int argc, char** argv)
 {
-    std::ios::sync_with_stdio(false);
+    // std::ios::sync_with_stdio(false);
     auto arguments = absl::ParseCommandLine(argc, argv);
     auto filesToParse = absl::MakeConstSpan(arguments).subspan(1);
     std::cout << "Positional arguments:";
-    for (auto& file: filesToParse)
+    for (auto& file : filesToParse)
         std::cout << " " << file << ',';
     std::cout << '\n';
 
     sfz::Synth synth;
     std::filesystem::path filename { filesToParse[0] };
-    synth.loadSfzFile(filename);  
+    synth.loadSfzFile(filename);
     std::cout << "==========" << '\n';
     std::cout << "Total:" << '\n';
     std::cout << "\tMasters: " << synth.getNumMasters() << '\n';
@@ -25,16 +156,80 @@ int main(int argc, char** argv)
     std::cout << "\tPreloadedSamples: " << synth.getNumPreloadedSamples() << '\n';
     std::cout << "==========" << '\n';
     std::cout << "Included files:" << '\n';
-    for (auto& file: synth.getIncludedFiles())
+    for (auto& file : synth.getIncludedFiles())
         std::cout << '\t' << file.string() << '\n';
     std::cout << "==========" << '\n';
     std::cout << "Defines:" << '\n';
-    for (auto& define: synth.getDefines())
+    for (auto& define : synth.getDefines())
         std::cout << '\t' << define.first << '=' << define.second << '\n';
     std::cout << "==========" << '\n';
     std::cout << "Unknown opcodes:";
-    for (auto& opcode: synth.getUnknownOpcodes())
+    for (auto& opcode : synth.getUnknownOpcodes())
         std::cout << opcode << ',';
     std::cout << '\n';
+    // std::cout << std::flush;
+
+    auto defaultName = "sfizz";
+    jack_status_t status;
+    client = jack_client_open(defaultName, JackNullOption, &status);
+    if (client == nullptr) {
+        std::cerr << "Could not open JACK client" << '\n';
+        // if (status & JackFailure)
+        //     std::cerr << "JackFailure: Overall operation failed" << '\n';
+        return 1;
+    }
+
+    if (status & JackNameNotUnique) {
+        std::cout << "Name was taken: assigned " << jack_get_client_name(client) << "instead" << '\n';
+    }
+    if (status & JackServerStarted) {
+        std::cout << "Connected to JACK" << '\n';
+    }
+
+    synth.setSamplesPerBlock(jack_get_buffer_size(client));
+    synth.setSampleRate(jack_get_sample_rate(client));
+
+    jack_set_sample_rate_callback(client, sampleRateChanged, &synth);
+    jack_set_buffer_size_callback(client, sampleBlockChanged, &synth);
+    jack_set_process_callback(client, process, &synth);
+
+    midiInputPort = jack_port_register(client, "input", JACK_DEFAULT_MIDI_TYPE, JackPortIsInput, 0);
+    if (midiInputPort == nullptr) {
+        std::cerr << "Could not open MIDI input port" << '\n';
+        return 1;
+    }
+
+    outputPort1 = jack_port_register(client, "output_1", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
+    outputPort2 = jack_port_register(client, "output_2", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);
+    if (outputPort1 == nullptr || outputPort2 == nullptr) {
+        std::cerr << "Could not open output ports" << '\n';
+        return 1;
+    }
+
+    if (jack_activate(client) != 0) {
+        std::cerr << "Could not activate client" << '\n';
+        return 1;
+    }
+
+    auto systemPorts = jack_get_ports(client, nullptr, nullptr, JackPortIsPhysical | JackPortIsInput);
+    if (systemPorts == nullptr) {
+        std::cerr << "No physical output ports found" << '\n';
+        return 1;
+    }
+
+    if (jack_connect(client, jack_port_name(outputPort1), systemPorts[0])) {
+        std::cerr << "Cannot connect to physical output ports (0)" << '\n';
+    }
+
+    if (jack_connect(client, jack_port_name(outputPort2), systemPorts[1])) {
+        std::cerr << "Cannot connect to physical output ports (1)" << '\n';
+    }
+    jack_free(systemPorts);
+
+    signal(SIGHUP, done);
+    signal(SIGINT, done);
+    signal(SIGTERM, done);
+    signal(SIGQUIT, done);
+    sleep(-1);
     return 0;
 }
\ No newline at end of file
diff --git a/sources/StereoBuffer.h b/sources/StereoBuffer.h
index 145c7503..b16d5f75 100644
--- a/sources/StereoBuffer.h
+++ b/sources/StereoBuffer.h
@@ -33,17 +33,23 @@ public:
         return false;
     }
 
-    absl::Span<const Type> getSpan(Channel channel) const
+    absl::Span<const Type> getConstSpan(Channel channel) const
     {
         switch (channel) {
         case Channel::left:
             return leftBuffer;
         case Channel::right:
             return rightBuffer;
-        // Should not be here by construction...
-        default:
-            ASSERTFALSE;
-            return {};
+        }
+    }
+
+    absl::Span<Type> getSpan(Channel channel)
+    {
+        switch (channel) {
+        case Channel::left:
+            return absl::MakeSpan(leftBuffer);
+        case Channel::right:
+            return absl::MakeSpan(rightBuffer);
         }
     }
 
@@ -55,10 +61,6 @@ public:
             return leftBuffer[sampleIndex];
         case Channel::right:
             return rightBuffer[sampleIndex];
-        // Should not be here by construction...
-        default:
-            ASSERTFALSE;
-            return trash;
         }
     }
 
@@ -152,9 +154,6 @@ private:
     static constexpr auto TypeAlignmentMask { TypeAlignment - 1 };
     static_assert(TypeAlignment * sizeof(Type) == Alignment, "The alignment does not appear to be divided by the size of the Type");
     int numFrames { 0 };
-    int totalSize { 0 };
-    int padding { 0 };
     Buffer<Type, Alignment> leftBuffer {};
     Buffer<Type, Alignment> rightBuffer {};
-    Type trash { 0 };
 };
diff --git a/sources/StereoSpan.h b/sources/StereoSpan.h
new file mode 100644
index 00000000..c1485c47
--- /dev/null
+++ b/sources/StereoSpan.h
@@ -0,0 +1,131 @@
+#pragma once
+#include "Helpers.h"
+#include "SIMDHelpers.h"
+#include "StereoBuffer.h"
+#include <absl/types/span.h>
+#include <type_traits>
+
+template <class Type>
+class StereoSpan {
+public:
+    using ValueType = std::remove_cv_t<Type>;
+    template <typename U>
+    StereoSpan() = delete;
+    StereoSpan(Type* leftBuffer, Type* rightBuffer, size_t numFrames)
+        : numFrames(numFrames)
+        , leftBuffer(leftBuffer, numFrames)
+        , rightBuffer(rightBuffer, numFrames)
+    {
+    }
+
+    StereoSpan(void* leftBuffer, void* rightBuffer, size_t numFrames)
+        : numFrames(numFrames)
+        , leftBuffer(static_cast<Type*>(leftBuffer), numFrames)
+        , rightBuffer(static_cast<Type*>(rightBuffer), numFrames)
+    {
+    }
+
+    StereoSpan(absl::Span<Type> leftBuffer, absl::Span<Type> rightBuffer)
+        : numFrames(std::min(leftBuffer.size(), rightBuffer.size()))
+        , leftBuffer(leftBuffer.first(numFrames))
+        , rightBuffer(rightBuffer.first(numFrames))
+    {
+        // Buffer really should be the same size here
+        ASSERT(leftBuffer.size() == rightBuffer.size());
+    }
+
+    StereoSpan(StereoBuffer<const ValueType>& buffer)
+        : leftBuffer(buffer.getConstSpan(Channel::left))
+        , rightBuffer(buffer.getConstSpan(Channel::right))
+        , numFrames(buffer.getNumFrames())
+    {
+    }
+
+    StereoSpan(StereoBuffer<ValueType>& buffer, size_t numFrames)
+        : numFrames(numFrames)
+        , leftBuffer(buffer.getSpan(Channel::left).first(numFrames))
+        , rightBuffer(buffer.getSpan(Channel::right).first(numFrames))
+    {
+    }
+
+    StereoSpan(const StereoBuffer<const ValueType>& buffer, size_t numFrames)
+        : numFrames(numFrames)
+        , leftBuffer(buffer.getConstSpan(Channel::left).first(numFrames))
+        , rightBuffer(buffer.getConstSpan(Channel::right).first(numFrames))
+    {
+    }
+
+    StereoSpan(StereoSpan<ValueType>& span)
+        : numFrames(span.size())
+        , leftBuffer(span.left())
+        , rightBuffer(span.right())
+    {
+    }
+
+    StereoSpan(const StereoSpan<const ValueType>& span)
+        : numFrames(span.size())
+        , leftBuffer(span.left())
+        , rightBuffer(span.right())
+    {
+    }
+
+    void fill(Type value) noexcept
+    {
+        ::fill<Type>(leftBuffer, value);
+        ::fill<Type>(rightBuffer, value);
+    }
+
+    void readInterleaved(absl::Span<const Type> input) noexcept
+    {
+        ASSERT(input.size() <= static_cast<size_t>(numChannels * numFrames));
+        ::readInterleaved<Type>(input, absl::MakeSpan(leftBuffer), absl::MakeSpan(rightBuffer));
+    }
+
+    void writeInterleaved(absl::Span<Type> output) noexcept
+    {
+        ASSERT(output.size() >= static_cast<size_t>(numChannels * numFrames));
+        ::writeInterleaved<Type>(leftBuffer, rightBuffer, output);
+    }
+
+    void add(StereoSpan<const Type> buffer)
+    {
+        ::add<Type>(buffer.left(), leftBuffer);
+        ::add<Type>(buffer.right(), rightBuffer);
+    }
+
+    absl::Span<Type> left()
+    {
+        return leftBuffer;
+    }
+
+    absl::Span<Type> right()
+    {
+        return rightBuffer;
+    }
+
+    StereoSpan<Type> first(size_t length)
+    {
+        return { leftBuffer.first(length), rightBuffer.first(length) };
+    }
+
+    StereoSpan<Type> last(size_t length)
+    {
+        return { leftBuffer.last(length), rightBuffer.last(length) };
+    }
+
+    StereoSpan<Type> subspan(size_t pos, size_t length = absl::Span<Type>::npos)
+    {
+        return { leftBuffer.subspan(pos, length), rightBuffer.subspan(pos, length) };
+    }
+
+    size_t size()
+    {
+        return numFrames;
+    }
+
+private:
+    static constexpr int numChannels { 2 };
+    size_t numFrames { 0 };
+    absl::Span<Type> leftBuffer;
+    absl::Span<Type> rightBuffer;
+};
\ No newline at end of file
diff --git a/sources/Synth.h b/sources/Synth.h
index 8d504a92..3a816b01 100644
--- a/sources/Synth.h
+++ b/sources/Synth.h
@@ -2,6 +2,7 @@
 #include "FilePool.h"
 #include "Parser.h"
 #include "Region.h"
+#include "StereoSpan.h"
 #include "SfzHelpers.h"
 #include "absl/types/span.h"
 #include <optional>
@@ -28,20 +29,27 @@ public:
     auto getUnknownOpcodes() { return unknownOpcodes; }
     size_t getNumPreloadedSamples() { return filePool.getNumPreloadedSamples(); }
 
-    void prepareToPlay(int samplesPerBlock, double sampleRate)
+    void setSamplesPerBlock(int samplesPerBlock)
     {
+        DBG("[Synth] Samples per block set to " << samplesPerBlock);
         this->samplesPerBlock = samplesPerBlock;
-        this->sampleRate = sampleRate;
-        this->tempBuffer = StereoBuffer<float>(samplesPerBlock);
+        this->tempBuffer.resize(samplesPerBlock);
     }
 
-    void renderBlock(StereoBuffer<float>& buffer)
+    void setSampleRate(double sampleRate)
+    {
+        DBG("[Synth] Sample rate set to " << sampleRate);
+        this->sampleRate = sampleRate;
+    }
+
+    void renderBlock(StereoSpan<float> buffer)
     {
         buffer.fill(0.0f);
         
+        StereoSpan<float> tempSpan { tempBuffer, buffer.size() };
         for (auto& voice : voices) {
-            voice->renderBlock(tempBuffer);
-            buffer.add(tempBuffer);
+            voice->renderBlock(tempSpan);
+            buffer.add(tempSpan);
         }
     }
 
@@ -83,7 +91,22 @@ public:
             }
         }
     }
-    void cc(int delay, int channel, int ccNumber, uint8_t ccValue);
+    void cc(int delay, int channel, int ccNumber, uint8_t ccValue)
+    {
+        for (auto& voice : voices)
+            voice->registerCC(delay, channel, ccNumber, ccValue);
+
+        for (auto& region : regions) {
+            if (region->registerCC(channel, ccNumber, ccValue)) {
+                auto voice = findFreeVoice();
+                if (voice == nullptr)
+                    continue;
+
+                voice->startVoice(region.get(), channel, ccNumber, ccValue, Voice::TriggerType::NoteOff);
+            }
+        }
+    }
+
     void pitchWheel(int delay, int channel, int pitch);
     void aftertouch(int delay, int channel, uint8_t aftertouch);
     void tempo(int delay, float secondsPerQuarter);
diff --git a/sources/Voice.h b/sources/Voice.h
index 1f316ad1..6dce2e9c 100644
--- a/sources/Voice.h
+++ b/sources/Voice.h
@@ -1,5 +1,6 @@
 #pragma once
 #include "StereoBuffer.h"
+#include "StereoSpan.h"
 #include "Globals.h"
 #include "Region.h"
 #include <atomic>
@@ -32,14 +33,20 @@ public:
         return (region == nullptr);
     }
 
-    void registerNoteOff(int delay, int channel, int noteNumber, uint8_t velocity);
-    bool registerCC(int delay, int channel, int ccNumber, uint8_t ccValue);
+    void registerNoteOff(int delay [[maybe_unused]], int channel [[maybe_unused]], int noteNumber [[maybe_unused]], uint8_t velocity [[maybe_unused]])
+    {
+
+    }
+    void registerCC(int delay [[maybe_unused]], int channel [[maybe_unused]], int ccNumber [[maybe_unused]], uint8_t ccValue [[maybe_unused]])
+    {
+
+    }
     void registerPitchWheel(int delay, int channel, int pitch);
     void registerAftertouch(int delay, int channel, uint8_t aftertouch);
     void registerTempo(int delay, float secondsPerQuarter);
 
     void prepareToPlay(int samplesPerBlock, double sampleRate);
-    void renderBlock(StereoBuffer<float>& buffer)
+    void renderBlock(StereoSpan<float> buffer)
     {
         buffer.fill(0.0f);
     }