Could use some help with a tough match

Hi Don,

No need for apologies, I'm just trying to figure out where you want to go here. It seems like you want a tube balanced preamp, am I wrong? Obviously your amp is a poor match for this, so you will need to either change amps, go balanced SS or single-ended if you want tubes.

FWIW, when you talk about simplicity of design, a single ended circuit is much simipler to implement than a balanced circuit, with approximately half the parts. So maybe it sounds like a single ended tube preamp is for you. There are many good single ended tube preamps out there, Shindo, Doshi, CAT, Joule, among many others. In fact, your choices amongst single ended tube preamps is far greater than your choices amongst fully balanced tube preamps.

If you wish you certainly could try a balanced tube preamp with your Threshold, nothing will blow up. The impedance matching is just to help the sound. With an impedance mismatch like you would be likely to have, would just make the sound rolled off at the frequency extremes.

IMHO you would be better served trying a nice single ended tube preamp with your amp.

Cheers,
John

BTW, I currently own a ARC Ref 3, great preamp. I can't say that I have compared the SE to the BAL though, as I've only run balanced. My amp has a 200K balanced input impedance though.

Thanks John,
The driver behind my change is I am in the process of upgrading. From what I have learned the general concensus is that a tube preamp is a better match for my Sonus Faber Amati's. So if I am going to change I might as well explore the world of tubes.
Cheers,
Don

FYI (and to the best of my knowledge), the earlier single ended Threshold amps are cap coupled. The later e series fully balanced Threshold amps are DC coupled. Some earler Threshold amps were upgraded to "e" series with balanced inputs, but are still cap coupled. Most tube pres are not DC coupled (the only ones I'm aware of are Atmasphere and Sonic Frontiers). Adding balanced inputs to your Threshold amps might help with long cable runs, but will other wise just add needless complexity. You might have more (though not necessarily better) tube pre options sticking with your single ended Threshold amp. On the other hand upgrading to newer fully balanced Threshold amps might offer better tube pre options, albeit at a cost. My previous recommendations for Audio Research and Sonic Frontiers comes from an ex Threshold tech with lots of expereince and feed back from Threshold customers. The c-j thought just seems to make sense. Why pay for expensive fully balanced operation if you won't use it. The really high end c-j pres output impedance might be cause for concern though.

Thank you Unsound. Excellent post, you have helped me crystalize my way forward. I will leave the Thresholds unbalanced because frankly I firmly believe they match up well with my speakers so will look for a single ended ARC, Sonic Frontiers or c-j preamp but welcome other suggestions. I looked at the ARC 3 but once again would be paying for technology ( balanced operations) I won't use. Any recommendations on a good ARC, Sonic Frontiers, or c-j models? I don't mind if its a few years old but I really want a quality unit. It will be the heart of my system so a class A component is essential ( quiet, big soundstage and dynamics ). I will start researching again but if anyone has a slam dunk recommendation I would appreciate your input.
Thanks,
Don

Don, if you are looking for a great single-ended preamp, I suggest that you do some research on this Shindo Monbrisson. They are a rare find on the used market.

FWIW, I have no connection with the seller.

Cheers,
John