Which amp matches best my JM Lab Mezzo Utopia ?

Aleko, wherever you read that tidbit, its not actually true. Also FWIW if the amplifier is balanced-differential you do not have 'doubled circuitry'. Differential circuits have the advantage of lower noise and lower distortion as opposed to their single-ended counterparts. This can be a big deal depending on the complexity of the amplifier. In single-ended circuits the distortion of one stage is compounded by the distortion of the following stage. Obviously a fully differential amplifier will be lower distortion.

Lower distortion is usually audible in 2 ways: more transparent (detailed) and more relaxed (regardless of bandwidth).

The Mezzo is a tube-friendly speaker, but does need some power to make it go. You will be a lot better off with 50-100 watts than you will be with 7-15 as a result. The speaker will literally wake up!

Hi Aleko,

I am not familiar with too many brands & amps.
I am using Dual Mono Block Tube Pre-Amp and Mon0-Block
Tube Power Amp ( P-P 300B ) and had them driving my
Mezzo Utopia for almost one year. Tube-rolling, ( of course only changing the 6SN7, 5U4 etc. not the WE 300B )
inter-connects/ power cables changing were all failure
to make it sound to satisfaction. So don't use Utopia
with 300B amps. (other tubes may be suitable more )

Because I like WE 300B so much, finally I had to change
to Parsifal from Utopia.

I remember wonderful combination of Mezzo with JRDG Concentra + MBL DAC + Helios Stargate as a cd drive. Don't remember name of the cables.

Has anyone tried the Mezzo with a single ended amp based on the 211 tube ?
Or with a parallel single ended amp based on 2 output tubes like the 211 or the 845 ?
Or the GM 70 tube ?
Any shared experience is welcome.

Thanks

As a current SET owner my Audio Valve Challenger Class A tube mono amps sound much better than any SET I have owned and I have owned over 30 SET amplifiers. SET are just a wee bit better in the midrange and its slight but everywhere else the AV stomp on my SETs.