Pls help me decide Pass Labs X250.8 or Luxman M900u

@yoyoyaya thank for the response , @audphile1  you make a very good point.

what specs do I need to look at to understand if the Backert Rhumba Extreme 1.4 would pair well with a Pass Labs X250.8 ?

https://backertlabs.com/tube-bias-adjusted-automatically/

https://backertlabs.com/more-goodies/

@garynospamm

I’ll chime in and I’m sure @yoyoyaya will as well…

few things to consider -

1. The input impedance of the amplifier should be at least 10x the output impedance of the preamplifier.
2. The amplifier input sensitivity and gain - pair a high gain preamp with a high gain amp and you’ll be losing some of the finesse of the preamp volume conttol as well as the volume range.
3. Figure out if you want to use XLR outs on a preamp - most preamps will double the voltage output on the XLR outs compared to their single ended outputs.

If you take the specs of the amp and preamp and reach out to their respective manufacturers, they’ll give you an idea if the pairing will work and or what aspects of sound quality may be compromised 

@audphile1

So, I found this on the Backert

Input impedance: 34,000Ω
Output impedance: Below 80Ω

On the Pass Labs X250.8 specs

So thoughts? Input 100,000 on amp

output on Pre 80ohms so looks good?

You’re fine as long as the sound characteristics work for you. 

Impedance is fine.