Sjöström Audio

http://sjostromaudio.com/pages/index.php/hifi-projects/130-qrv09-headphone-amp
Click on the picture to see a larger view of the pcb. The performance is outrageous in headphone amp terms. See the technical data! Interesting features: The pcb fits virtually any single opamp Room for good coupling caps (if you must or like)...
https://audio-circuit.dk
Jan Dupont has a big collection of schematics and service manuals for all sorts of audio equipment, such as amplifiers and loudspeakers.
http://www.audiosector.com
Peter Daniel in cooperation with Brian Bell has designed this little cute and blue Gainclone pcb. A very nice job indeed. Mr. Daniel also sells pcb's for a good price. At the moment this is the only place to hold of the real gainclone pcb since chipamp...
https://www.muffsy.com/muffsy-pp4.html
A nice looking RIAA phono amp based on NE5532 or OPA2134 but you change the opamp to something else. The design has a passive RIAA equalisation.
http://www.audiophonics.com
Ms. Susan Parker has a collection of rather unusual stuff like a zero-feedback amplifier consisting of only two MOSFET's! She has also designed a loudspeaker made of marble!
http://www.tentlabs.com
Mr. Guido Tent's homepage with lot's of good DIY stuff, such as CD clocks and super shunt regulators.
http://www.weiss.ch/products/op1-bp
A discrete built operational amplifier with of course ultra high performance. It looks real good also.
http://sjostromaudio.com/pages/index.php/hifi-projects/132-qsxm2-the-extreme-phono-riaa-amplifier
QSX Mark II - The extreme phono (RIAA) amplifier   Click on the picture to get a larger view. The front view of the original QSX Amplifier from 1986. Click on the picture to get a larger view. The top view of the QSX Amplifier pcb. High...
http://www.vikash.info/audio/
Vikash Chauhan has DIY Audio site containing LM3875 and LM3386 based power amplifiers and various other audio projects such as loudspeakers.
http://www.keld.eu/diy
This is Keld's DIY site that contains various projects including my QRP01. Original here.
http://www.parttimeprojects.com/audio/diy
DIY audio projects, including a differential input (buffered) LM3886 GainClone amplifier, an LM4780 parallel ChipAmp, a Krell KSA 50 Clone, a preamplifier, a battery powered differential line driver, a soft start circuit, and a few .wav files of audio...
http://www.s-audio.com
A very nice gainclone design with ultra low distortion signed by Nickolay Shvydky. The pcb uses SMD parts and looks very nice, indeed.