What's the best sounding replacement for 12AX7A and 12AT7?

In place of the 12AX7's you may want to find 5751's which are the mil. spec. version, old RCA's and Sylvania's.

Although both of the other suggestions above are excellent, great bass in a 12AT7 always makes me think Telefunken. From personal experience, the earlier Atmasphere circuits were transformed by the Tele's. I would be surprised if they did not work magic in your Jolida.

For 12ax7, try a 7058 (RCA made good ones). They are cheap and sound amazing.

For 12at7, try a GE or Sylvania 6201.

A very good tube equivalency resource is:

http://www.duncanamps.co.uk/

Talk with Andy Bowman at Vintage Tube Services (www.vintagetubeservices.com). This guy is the real deal! His supply, service, knowledge, testing expertise and equipment, and experience make you realize that all of the other so called "experts" really don't have a clue...and I've dealt with most of 'em.

I would suggest that you talk to Andy at Vintage Tube Services. He has been in the business (his only business) since the mid 80's and this has been an avocation for him virtually his whole life. His web page is www.vintagetubeservices.com or better yet call him at 616-454-3467.

His suggestions regarding replacing my 12AX7's from my Aronov preamp worked magic...much more musical and detailed. I also hate to burst your bubble but there are many grades of 6550's and what is currently out there is definitely substandard compared to the NOS Tungsols and Sylvanias. I should know. Andy put together some NOS Sylvanias and WOW!

At any rate it would definitely be to your benefit to call him.