What is the best tube pre-amp for my system

Snooker,

I really like the Ayon family sound and the Spheris is the preamp in my dream system (the amp is the Ayon Titan mono blocks). Still, auditioning the Spheris with your Pass x350.8 amps would certainly seem prudent.

I read the specifications for the Spheris and it listed an output impedance of 30 Ohms. The single ended/balanced impedance of the X350.8 was given as 50/100 kOhms. From what I've read related to rules of thumb for preamp/amp matching, it seems like that should be a good ratio, but I would defer to more learned members of this forum, or better yet I would call Pass Labs to discuss.

On another note, should you ever decide to move from the CD-5 to a media player, I highly recommend the Ayon S-5.

Thank you Reynolds. Perhaps I will look at the S-5 in the near future. I will
call Pass tomorrow. I also wondered about that. I will have 15 days to audition the Spheris, which is a good thing.....

If you buy used you get to try in your room with your system. If you don't like it you can sell used and get your money back. It's the only way short of a thirty day dealer demo.

A sound recommendation. But I have yet to find a used one on the market....

Snooker14 hi, Have you tried direct connection between your Ayon CD5 and Pass 350.8?

As the Ayon has output level control at it's lowest setting from 0-4V variable.

And your Pass amp is 50kohm input impedance and only needs 2v in to drive it to max output.

So as you can see you don't need more electronics and gain in the signal path.
As doing a direct connection from Ayon to the Pass is a perfect match, impedance, gain and drive, and will give you the most transparent sound you can get, also save you a stack of money not getting a preamp.

Unless you wish to add some colouration by using preamp, then you will have the added problem of way too much gain.

Cheers George