I'm listening to a 6AH4 line stage as I write. As a previous poster said, it really is shockingly good. It's not quite a DHT like 26, 47 or 10Y, but for an indirectly heated tube it's unusually satisfying. All the detail and tone you could want. Since output impedance is around 1.8K it should drive most amps. I use it as the input stage for my EL12n SE outputs and this gives you a very nice 2 stage amp. Simple to build and very good sound, which would see off the majority of SE tube amps. The parts are important - FT-2 teflon coupling caps and Kemet DC Link bypasses and last PSU cap. And top quality wirewound resistors. It's good on jazz, opera, classical and pretty much whatever you throw at it.
