What's the best EL84 amp?

@dhcod: If you want to experience a hot amp, get a pair of mono Atma-Spheres. A pair of M-60's run 16 output tubes (in Class A), for a mere 60 watts//ch!

One day when we have some good A/C!

@bdp24 More people than one would have expected have told us they felt the RM-9 MkII sounded more like a solid state amp than a tube amp. It was certainly a lower distortion amp, with an upgraded power supply featuring added filter capacitance and chokes, but 8 x EL-34s for output tubes is 8 x EL-34s so go figure.

While Dick Olsher preferred the original RM-9 fitted with KT88’s in place of the standard EL-34’s, in the Mk.2 version he preferred the stock EL-34’s, finding the KT-88’s to imbue the Mk.2 with "a subtle, bright tinge through the upper mids and lower treble, and to reproduce the lower mids and upper bass less fully fleshed out." Now THAT sounds like the description of a typical solid state amp!

By the way, SkyFi Audio currently has an RM-9 (original) in stock, priced at $3499. For those who found tube amps to go through tubes too quickly (ARC, anyone? ;-), in the RM-9 the EL-34’s are biased at only 30 milliamps, resulting in low plate dissipation, therefore cool running tubes with a typical lifespan of about 10,000 hours. 10,000!

But Roger ended up, I believe, liking the RM-10 even more than the RM-9. At the talk he gave at Brooks Berdan Ltd to introduce the RM-10, I asked Roger if he recommended a single RM-9 over a pair of RM-10’s for use with stacked Quads (my speakers at the time), and he told me a single RM-9, as it’s greater power output would better prevent overload/clipping with the demanding load stacked Quads present an amp.

The next time I saw him he told me he had been thinking about my question, and had changed his mind. I know he had a pair of Quads himself, and after living with the Quad/RM-10 combination had come to REALLY like their synergy. In my humble opinion, the RM-10 is THE amp for the Quad ESL.

Roger was an enthusiastic proponent of using a pair of subs with the Quad, crossed over at 100Hz with a steep filter (symmetrical 24dB/octave). If you’re going to do it, look into the Rythmik/GR Research OB/Dipole Sub. In my opinion, THE sub for use with the Quad, or any dipole loudspeaker, for that matter.

I like the EL84 tube and once owned a custom-made amp using that tube.  Of commercial amps of current manufacture, I like the Audio Note OTO, which is a somewhat pricey integrated amp. 

For vintage amps, I think that the Eico HF81 amps were quite good.