Mac has a superior design and superior knowledge of how to make tube amps. And until someone knows what Mac people know about winding and constructing transformers they are trying to build amps with both arms tied behind their backs!. Its the same knowledge that allows Mac to use Autoformers where others wouldn't dream of it. My old Crown amps while meeting specs at 8 ohms, 180 watts a channel at 240 watts across 4 ohms the distortion we nt from about 1% at 10 ,000 hz to over 7% by 14,000 hz. You don't see that with 2105 or 2205s's. Even 7200's with out autoformers still equaled or bettered 7300s at lower impedances over the full sound spectrum.