newguy, FYI, I have done a dozen or so of the CMoys on the Radio Shack board. The last one I finally hit something special in comparison to all the others. First of all, I don't worry about trying to squeeze everything into a mint tin. I did that on the first one and the novelty of that wore off before I was even finished. I certainly recommend ordering from Mouser or Digi-Key or some such supplier. It's much cheaper in the end, even with shipping charges. And the quality comparison isn't even fair. You could buy 2 parts with the same Radio Shack part number and I'm not sure they would even be from the same supplier. On the amp in question, I used an OPA2132P op-amp($8.41@Digi-Key), Nichicon UPW1C102MPD 1000uF 25V capacitors(12.5mmx20mm, .76/each@Mouser), Vishay/Roederstein .47uF metal film input capacitors(.48/each), Vishay/Dale RN55D resistors(.11/each), the Alps 9mm pot from Tangent, Switchcraft jacks, and the sound quality and "pop" is amazingly different from the other Cmoys. I run it with dual 9V batteries. I've tried different op-amps, capacitors, resistors, yada yada yada, and I even built one using all Radio Shack parts, including the op-amp and sockets. That was a joke. This one stands far and away above the others. I make no claims to have enough electronics knowledge to explain why, but I do know the end result. I have over 35 years of critical listening to some pretty decent gear. It has very nice bass punch and is surprisingly less "harsh"(than my other CMoys) in the high frequencies with my 32 ohm Grado SR60s, which I feel are notorious for harshness. With my son's Beyers(also 32 ohm), the high end is almost too laid back(maybe that's from too many years of Grados), but the midrange detail and clarity is truly phenomenal for a $30 amp. The gain is set at 11, which is great for using with my Philips portable CD headphone output. I can max out the pot without it being dangerously loud. However, connected to the line level of my component Denon CD player, it plays at an extreme(dangerous) volume level. There's a bit of a tradeoff in sound quality using the phone output of the portable. It just ain't got IT when compared to the Denon. If someone had no reference like that, and had only heard this set up with the portable, I believe they would be duly impressed. You will want to tailor the gain, depending on your intended use. Having said that, it is what it is, a CMoy. Have fair expectations and you will be surprised at how good these can sound for a few bucks.
