Low gain power amp to match the Audio Note M6 pre

Well you could just use some Rothwell attenuators on your M6's output, then you could choose any amp you want.

I used to have a Nait 5i. I don't remember it having a pre input. If you are just connecting it to a line level input, thats the problem. You're using 2 preamps.

I have used in-line attenuators, as Jncgrogan2 suggested above, and they do work well. For some reason, that I cannot recall, the recommended location of attenuators is on the input side of the linestage rather than the outputs. I used the attenuators on the output because I did not buy the three sets I would have needed for inputs.

An Audionote M-6 is sort of overkill for $3,000 amps, unless they are interim items in a planned upgrade. I have heard various versions of Sophia amps (cannot recall the model) and they have all sounded decent for the money. The issue with that company is quality control and the owners penchant for constantly substituting parts and being a somewhat flaky person to deal with (I live close by, and when buying a set of tubes he insisted that I meet his wife in the parking lot of a nearby McDonalds; I would be recognized by the model of car I drove, and his wife would flash her headlights three times. I was afraid the cops would think a drug deal was going down).

I heard a Decware amp recently and thought it was extremely bad sounding--muddled, utterly lacking in bass and bass control and lifeless. It was hastily installed in a system merely to check out if it was operational, so I cannot say how it would sound under ideal conditions. But, I was not encouraged by what I heard and suspect that they may be something that is excessively hyped on the internet.

For lower cost tube gear, I like the pushpull amps from Synthesis Audio. Most of their amps are integrated amps, but, I believe they have an EL34 amp and a 300b amp near your price range.

Just wanted to respond to Larryi's Decware comment. I've heard Decware amps a few times now and they were nothing at all like what Larryi described. I'm thinking he either heard a defective unit or was trying to drive speakers that the Decware was not designed to drive.

I always appreciate Larryi's comments and observations. I do wonder if that
amp may have been mated to an inappropriate speaker load. The Decware
amps are often highly praised( have not heard one personally )I don't doubt
Larryi heard
what he heard in this particular circumstance. You can make any amplifier
sound poor with the wrong speaker.
Regards,