Preamp upgrade

Performance as concerns sound is foremost, but given the already curated list, I would assume any of the mentioned ones would be enjoyable. I would include in my consideration whether the maker was a large enough company to credibly provide support for as long as you would expect to own the component, meaning parts, a network of supported repair shops and if new, a reasonably long warranty. Unless you have money to burn, low-volume products from atelier-type producers are out. If you are buying used and at substantial discount from new purchase prices, you will have to weigh the risk of replacing the unit sooner than you would like for lack of parts and support. I have always thought AR made components that were well-engineered and well-constructed and durable, yet still, they are a company that has had its ups and downs in recent years (I still would buy their gear, FWIW.) Other outfits, it would depend.

@chenry I always look for point to point wired tube equipment that all the parts are easily sourced and available, there are many small manufacturers that do this. Some of the bigger manufacturers may use circuit boards that later are discontinued, so buying from a bigger well know manufacturer doesn't always mean you can easily get the item repaired.

jelliott78

I would highly recommend you look at these tube preamps. All are hand made, point to point wired, using the highest quality components:

Aric Audio Motherlode II (RCA only $5,475), Aric Audio Motherlode XL (RCA & XLR $6,475), Don Sachs/Lynn Olson Raven preamp $5,895, or Supratek Cabernet $4,000 or Supratek Grange $6,000

For transparency, I do own the Aric Audio Motherlode XL......best preamp that I have ever heard. The Raven was really really close, and could live with it for life too

I am wondering if the preamp upgrade for thousands more will provide any real marginal gain.

@jelliott78 The short and long answers both involve 'yes'.

Since your amps support balanced line, I would consider a balanced line preamp so as to get the most out of the cables and the amps. The balanced line system has standards in place that have been there for decades. Not all balanced preamps in high end audio support the standards. The standards are useful as they prevent coloration from interconnect cables and also prevent ground loops.

The main standard is known as AES48. You can ask the manufacturer of a potential preamp if its supported. The second aspect is the ability to drive a lower impedance such as 600 Ohms. This is harder for a tube preamp but they do exist. If you get a preamp that supports both aspects of balanced line operation you won't have to worry about what cable sounds the best ever again; to my thinking that's a real benefit!

Good Luck on the quest!