This is my latest addition...a Quad 707 power amp!  It's not DIY, and it's not tube based but it sounds really good.  Compared to my tube amps the bass through the Quad 63 ESL speakers is very solid and fast.  This is definitely a good amp!

Specifications:

130 watts into 8 ohms and 220 watts into 4 ohms

Signal to Noise ratio 105dB

775mV input for maximum power out

20K ohm input impedance

Distortion is less than 0.01% at 130 watts

Dimensions B x H x T  321mm x 138mm x 240mm

Weight 12Kg

Low quality copies of the manual for the 707 can be downloaded here and the 77 series brochure here.