My Perfect Headphone System (for now)

hd650 from Senheisser
3322 from Darkvoice (Mullard)
Carat Ruby from Carat

It's a mix of German+Chinese+Korean. Ruby is powered by a dry battery to ensure the clean power. This DAC is probably one thing I can improve. But so far I'm very satisfied.

Updated (January 2011):
Styleaudio has Ruby 2. Here are some changes. Key is USB Controller now can accept 96kHz/24 bit

Carat-Ruby Key Spec
1. MAIN DAC : BURR-BROWN PCM1792
- 24-Bit 192-kHz Sampling Advanced-Segment Audio Stereo DAC
- Dynamic Range: 127 dB / THD+N: 0.0004%
- 8x Oversampling Digital Filter
2. DIGITAL COTROLLER : CIRRUS LOGIC CS8416
- 32kHz to 192kHz Sample Frequency Range
- Low-Jitter Clock Recovery
3. USB COTROLLER : BURR-BROWN PCM2707
- FULL SPEED TRANCIEVER(REAL AUDIO 1.1)
- 32kHz ~ 48 kHz/ 16BIT DELTA-SIGMA STEREO
4. OPAMP : TOTAL 8PCS(DIP TYPE)
- I/V : TEXAS INSTRUMENTS NE5534 × 4PCS
- OUTPUT : ANALOG DEVICE AD817 × 2PCS
- HEADPHONE : BURR-BROWN OPA2134 × 2PCS

Carat-Ruby 2 Key Spec
1. MAIN DAC : BURR-BROWN PCM1796
- 24-Bit 192KHz Sampling Advanced-Segment Audio Stereo DAC
- Dynamic Range : 123dB / THD+N : 0.0005%
- 8x Oversampling Digital Filter
2. DIGITAL CONTROLLER : CIRRUS LOGIC CS8416
- 32KHz to 192KHz Sample Frequency Range
- Low-Jitter Clock Recovery
3. USB CONTROLLER : TE7022L
- USB 2.0 FS DAC / Fully Compliant With USB 1.1 Specification
- INPUT : 32KHz/16Bit ~ 96KHz/24Bit
4. OPAMP : TOTAL 8PCS(DIP TYPE)
- OUTPUT : TEXAS INSTRUMENTS OPA604 x 2PCS
- I/V : TEXAS INSTRUMENTS NE5534 x 4PCS
- HEADPHONE : BURR-BROWN OPA2134 x 2PCS