diff --git a/higan/GNUmakefile b/higan/GNUmakefile
index 9d9af1a2..5307f340 100644
--- a/higan/GNUmakefile
+++ b/higan/GNUmakefile
@@ -1,23 +1,24 @@
 include ../nall/GNUmakefile
 
 target := tomoko
+objects := libco emulator audio video resource
+build := release
 # console := true
 
-flags += -I. -I.. -O3
-objects := libco emulator audio video resource
+flags += -I. -I..
 
-# profile-guided optimization mode
-# pgo := instrument
-# pgo := optimize
-
-ifeq ($(pgo),instrument)
-  flags += -fprofile-generate
+ifeq ($(build),release)
+  flags += -O3
+  link += -s
+else ifeq ($(build),debug)
+  flags += -g
+else ifeq ($(build),instrument)
+  flags += -O3 -fprofile-generate
   link += -lgcov
-else ifeq ($(pgo),optimize)
-  flags += -fprofile-use
+else ifeq ($(build),optimize)
+  flags += -O3 -fprofile-use
 endif
 
-# platform
 ifeq ($(platform),windows)
   ifeq ($(console),true)
     link += -mconsole
diff --git a/higan/emulator/emulator.hpp b/higan/emulator/emulator.hpp
index d16eb5ab..ce95e184 100644
--- a/higan/emulator/emulator.hpp
+++ b/higan/emulator/emulator.hpp
@@ -12,7 +12,7 @@ using namespace nall;
 
 namespace Emulator {
   static const string Name    = "higan";
-  static const string Version = "102.04";
+  static const string Version = "102.05";
   static const string Author  = "byuu";
   static const string License = "GPLv3";
   static const string Website = "http://byuu.org/";
diff --git a/higan/pce/cpu/io.cpp b/higan/pce/cpu/io.cpp
index f3772bdc..c821dbda 100644
--- a/higan/pce/cpu/io.cpp
+++ b/higan/pce/cpu/io.cpp
@@ -134,8 +134,7 @@ auto CPU::write(uint8 bank, uint13 addr, uint8 data) -> void {
 
     //$0800-0bff  PSG
     if((addr & 0x1c00) == 0x0800) {
-      io.mdr = data;
-      return;
+      return psg.write(addr, io.mdr = data);
     }
 
     //$0c00-0fff  Timer
diff --git a/higan/pce/interface/interface.cpp b/higan/pce/interface/interface.cpp
index 2cc12159..c65ed795 100644
--- a/higan/pce/interface/interface.cpp
+++ b/higan/pce/interface/interface.cpp
@@ -75,7 +75,7 @@ auto Interface::videoColor(uint32 color) -> uint64 {
 }
 
 auto Interface::audioFrequency() -> double {
-  return 44'100.0;  //todo: not accurate
+  return 315.0 / 88.0 * 1'000'000.0;  //3.57MHz
 }
 
 auto Interface::loaded() -> bool {
diff --git a/higan/pce/psg/channel.cpp b/higan/pce/psg/channel.cpp
new file mode 100644
index 00000000..33a05e8e
--- /dev/null
+++ b/higan/pce/psg/channel.cpp
@@ -0,0 +1,31 @@
+auto PSG::Channel::power() -> void {
+  memory::fill(&io, sizeof(IO));
+  memory::fill(&output, sizeof(Output));
+}
+
+auto PSG::Channel::run() -> void {
+  if(!io.enable) return sample(0);
+
+  if(io.noiseEnable) {
+    if(--io.noisePeriod == 0) {
+      io.noisePeriod = ~io.noiseFrequency << 7;
+      //todo: this should be a square wave; PRNG algorithm is also unknown
+      io.noiseSample = nall::random();
+    }
+    return sample(io.noiseSample);
+  }
+
+  if(io.direct) return sample(io.waveDirect);
+
+  if(--io.period == 0) {
+    io.period = io.frequency;
+    io.waveOffset++;
+  }
+
+  return sample(io.waveData[io.waveOffset]);
+}
+
+auto PSG::Channel::sample(uint5 sample) -> void {
+  output.left = sample << 8;  //<< io.volume << io.volumeLeft;
+  output.right = sample << 8;  //<< io.volume << io.volumeRight;
+}
diff --git a/higan/pce/psg/io.cpp b/higan/pce/psg/io.cpp
new file mode 100644
index 00000000..9b7abb39
--- /dev/null
+++ b/higan/pce/psg/io.cpp
@@ -0,0 +1,81 @@
+auto PSG::write(uint4 addr, uint8 data) -> void {
+  if(addr == 0x00) {
+    io.channel = data.bits(0,2);
+    return;
+  }
+
+  if(addr == 0x01) {
+    io.volumeRight = data.bits(0,3);
+    io.volumeLeft = data.bits(4,7);
+    return;
+  }
+
+  uint3 C = io.channel;
+
+  if(addr == 0x02) {
+    if(C == 6 || C == 7) return;
+    channel[C].io.frequency.bits(0,7) = data.bits(0,7);
+    return;
+  }
+
+  if(addr == 0x03) {
+    if(C == 6 || C == 7) return;
+    channel[C].io.frequency.bits(8,11) = data.bits(0,3);
+    return;
+  }
+
+  if(addr == 0x04) {
+    if(C == 6 || C == 7) return;
+    if(channel[C].io.direct && !data.bit(6)) {
+      channel[C].io.waveOffset = 0;
+    }
+    if(!channel[C].io.enable && data.bit(7)) {
+      channel[C].io.waveOffset = 0;
+      channel[C].io.period = channel[C].io.frequency;
+    }
+    channel[C].io.volume = data.bits(0,3);
+    channel[C].io.direct = data.bit(6);
+    channel[C].io.enable = data.bit(7);
+    return;
+  }
+
+  if(addr == 0x05) {
+    if(C == 6 || C == 7) return;
+    channel[C].io.volumeRight = data.bits(0,3);
+    channel[C].io.volumeLeft = data.bits(4,7);
+    return;
+  }
+
+  if(addr == 0x06) {
+    if(C == 6 || C == 7) return;
+    if(channel[C].io.direct) {
+      channel[C].io.waveDirect = data.bits(0,4);
+    } else if(!channel[C].io.enable) {
+      uint5 O = channel[C].io.waveOffset++;
+      channel[C].io.waveData[O] = data.bits(0,4);
+    }
+    return;
+  }
+
+  if(addr == 0x07) {
+    if(C != 4 && C != 5) return;
+    if(!channel[C].io.noiseEnable && data.bit(7)) {
+      channel[C].io.noisePeriod = ~data.bits(0,4) << 7;
+      channel[C].io.noiseSample = 0;
+    }
+    channel[C].io.noiseFrequency = data.bits(0,4);
+    channel[C].io.noiseEnable = data.bit(7);
+    return;
+  }
+
+  if(addr == 0x08) {
+    io.lfoFrequency = data;
+    return;
+  }
+
+  if(addr == 0x09) {
+    io.lfoControl = data.bits(0,1);
+    io.lfoEnable = data.bit(7);
+    return;
+  }
+}
diff --git a/higan/pce/psg/psg.cpp b/higan/pce/psg/psg.cpp
index 7922e163..123d760f 100644
--- a/higan/pce/psg/psg.cpp
+++ b/higan/pce/psg/psg.cpp
@@ -3,14 +3,28 @@
 namespace PCEngine {
 
 PSG psg;
+#include "io.cpp"
+#include "channel.cpp"
 
 auto PSG::Enter() -> void {
   while(true) scheduler.synchronize(), psg.main();
 }
 
 auto PSG::main() -> void {
+  uint left = 0, right = 0;
+
+  for(auto C : range(6)) {
+    channel[C].run();
+    if(C == 1 && io.lfoEnable) {
+      //todo: frequency modulation of channel 0 using channel 1's output
+    } else {
+      left += channel[C].output.left;
+      right += channel[C].output.right;
+    }
+  }
+
+  stream->sample(left / 32768.0, right / 32768.0);
   step(1);
-  stream->sample(0.0, 0.0);
 }
 
 auto PSG::step(uint clocks) -> void {
@@ -19,8 +33,11 @@ auto PSG::step(uint clocks) -> void {
 }
 
 auto PSG::power() -> void {
-  create(PSG::Enter, 44'100.0);
-  stream = Emulator::audio.createStream(2, 44'100.0);
+  create(PSG::Enter, system.colorburst());
+  stream = Emulator::audio.createStream(2, system.colorburst());
+
+  memory::fill(&io, sizeof(IO));
+  for(auto C : range(6)) channel[C].power();
 }
 
 }
diff --git a/higan/pce/psg/psg.hpp b/higan/pce/psg/psg.hpp
index 234bb61f..575f595b 100644
--- a/higan/pce/psg/psg.hpp
+++ b/higan/pce/psg/psg.hpp
@@ -8,6 +8,49 @@ struct PSG : Thread {
   auto step(uint clocks) -> void;
 
   auto power() -> void;
+
+  //io.cpp
+  auto write(uint4 addr, uint8 data) -> void;
+
+private:
+  struct IO {
+    uint3 channel;
+    uint4 volumeLeft;
+    uint4 volumeRight;
+    uint8 lfoFrequency;
+    uint2 lfoControl;
+    uint1 lfoEnable;
+  } io;
+
+  struct Channel {
+    //channel.cpp
+    auto power() -> void;
+    auto run() -> void;
+    auto sample(uint5 sample) -> void;
+
+    struct IO {
+      uint12 frequency;
+      uint4  volume;
+      uint1  direct;
+      uint1  enable;
+      uint4  volumeLeft;
+      uint4  volumeRight;
+      uint5  waveData[32];
+      uint5  waveOffset;
+      uint5  waveDirect;
+      uint5  noiseFrequency;  //channels 4 and 5 only
+      uint1  noiseEnable;     //channels 4 and 5 only
+
+      uint12 period;
+      uint12 noisePeriod;
+      uint5  noiseSample;
+    } io;
+
+    struct Output {
+      uint left;
+      uint right;
+    } output;
+  } channel[6];
 };
 
 extern PSG psg;