Sony SCD XA5400ES tube rolling?

i'm buying a pair of rca grey glass from the 40's.

while i would prefer the brimars, they are hard to get and very expensive.

Just my 2 cents but $200 for a pair of Chinese 6SN7's seems a bit much even if the Sophia's do sound very good. There's still plenty of NOS available and most for less money.

Life expectancy would also be a concern for me. In addition to owning numerous versions of NOS 6SN7's, I still have several NOS Telefunken E88CC(6922) and ECC83(12AX7) tubes that have been used in five CAT preamps over more than a dozen years. Those tubes still test like new. The Sovtek's and Electro Harmonix that came with my first CAT didn't last 1500 hours. Yah, I know, we're talking 6SN7's but I'm guessing any good NOS will last waaay longer than anything produced today. Some of those old 6SN7's were rated for 10,000 hours!

"There's still plenty of NOS available and most for less money."

Yes, you're right, unfortunately you don't always know what you are getting and it really is a minefield out there without a reliable tube source. I highly recommend Andy Bowman of Vintage Tube Services towards that end. What I have found over the years is how important matching plays into the total equation of the overall impressions you hear when listening. I'm certainly not against NOS tubes providing you have a trusted source with measurements. I have plenty in my catche and I can attest to how good they can be. Unfortunately supply has dwindled and there are inflated prices on some of these tubes, especially the ones in greater demand, the Tung Sol round plates come to mind. It isn't this better than that more than with the Sophia Premium tubes you KNOW what you are getting, they are culled and carefully matched. The end results may vary in a given application but I will say this, I wouldn't give them such high praise if I didn't recognize what they bring to the table, at least in my application and 9 years of experience in my situation. I have no affiliation with Sophia and as always, YMMV. I do encourage the individuals that make the committment to post their impressions to lend balance to the discussion. Initial impressions should be IMMEDIATELY apparent aside from break-in considerations.

Tubegroover, I agree with everything you said. Yep, Andy Bowman would be a good source and his prices are reasonable. Matching too is important and you want low noise.

There are many sources for the more common and inexpensive 60's & 70's RCA's, Sylvania's, Tungsol's and GE's and most of them sound much better than the current stuff. Besides Andy, there are quite a few other legitimate tube dealers who offer these tubes with matching available.

Much of my collection has been purchased on Ebay from sellers who have lots of mostly 100% positive feedback and who show test results, AND guarantee those test results or your money back. I also have a Hickok tester so I'm able to test everything I buy. If you can't test your own, then as I said, there are many legitimate dealers you can turn to.

Well the Sophia's arrived yesterday and I popped them in and noticed an increase in resolution, a wider soundstage and more 3D. If you are looking for tubes to add warmth coloration- look else where. These tubes are very neutral and linear. I also notice a subtle tilt toward the treble and other reviews say this will resolve itself as it breaks in (up to 300 hrs). Even with that, I like the Sophia Electric sound better than my nos Sylvania's in my Modwright Oppo 83.

I'm glad I tried these. Thanks for the recommendation!