"One thing you should know is that DIY stuff generally costs more than store-built"
Yup. However, there are ways to finesse that. The first thing is to understand what is expensive and what isn't. Transformers, power supply filter caps, heatsinks, connectors (RCA, binding posts, etc) and enclosures are where most of the cost goes.
You can reduce costs a lot if
A- you don't care what it looks like. Usable enclosures can be found by scrounging - giant cookie tins that you may have gotten from your aunt last Christmas, 20mm ammunrtion boxes from a surpluss store (also commonly available through white water rafting sources), dead 486 PCs - etc. You can even substitute nuts and bolt from the harware store for binding posts (look at the back of some old 70's recieveiers).
B- Find an electronics surplus shop.
C- Shamlessly beg friends and relatives for old electronics geat in the garage, basement, closet, and attick __ You are looking for primarily for a suitable heatsinks, transformer(s) and filter caps. An enclosure might turn up too. Maybe even power switches and fuse holders - but be sure the current rating is adequate.
D-Stick to something simple like the Prpject P3A at
www.sound.au
E- Hardest of all is step away from your (our, my?) audiophillic midset: 5% resistors ARE OK most of the time, gold plate is nice but not neccessary, film and ceramic caps desoldered from an old VCR still function, etc. Instead, try the mindset that building a good sounding amp for next to nothing is a challenge - make it a goal instead of a limitation.
Check e-bay. Particularly for heatsinks and transformers.
Finally, (having had some less than fabulous experience with Sony gear) consider that perhaps you don't need more watts so much as better watts. My Sony (long gone) skimped on heatsinking and transformer VA rating - 4-ohm speakers killed it. I bet yours does too. The P3A, above, configured for a solid
[email protected] (70-80 @ 4?) will probably sound beter than the Sony. If it were me I would be looking for a 24-0-24 transformer with a max of 300VA and 14,000uF to 20,000uF of filter capacity -- this is certainly scroungable -- as far as collecting the "stuff", it's easier after that.
