@dkerr
I have both the original M1 and the current M1+ with the new volume control that rectifies the high gain issue completely and appears from memory to be a slight bit warmer than the original but that could just be a perception from having more flexibility with the volume control.
As to the issue of the M7 and tube preamps. I didn't really think the match with the BHK was bad just didn't have the warmth and magic that the pairing with the two 6SN7 preamps have. Though the BHK has some degree of the tube feel and more so with the 12 volt tubes it's not at all like what you get from a 6SN7 preamp. I do think the M7 is a great amp on it's own but it will not and does not sound like a tube amp. It is neutral and honest. The closest thing to it that I have owned was the JOB 225. What you put in was what you got out. My BHK 250 and AVA SET 400 are far "warmer". So how the pairing of your preamp and the M7 would go would depend mostly on where on the warmth scale your preamp is.
I have both the original M1 and the current M1+ with the new volume control that rectifies the high gain issue completely and appears from memory to be a slight bit warmer than the original but that could just be a perception from having more flexibility with the volume control.
As to the issue of the M7 and tube preamps. I didn't really think the match with the BHK was bad just didn't have the warmth and magic that the pairing with the two 6SN7 preamps have. Though the BHK has some degree of the tube feel and more so with the 12 volt tubes it's not at all like what you get from a 6SN7 preamp. I do think the M7 is a great amp on it's own but it will not and does not sound like a tube amp. It is neutral and honest. The closest thing to it that I have owned was the JOB 225. What you put in was what you got out. My BHK 250 and AVA SET 400 are far "warmer". So how the pairing of your preamp and the M7 would go would depend mostly on where on the warmth scale your preamp is.