5751 is really a little different from the ECC83 though there are certainly many / some simularities. I have an amp that uses 5751 that doesn't use ecc83. It also uses separate E182CC and 5687 that many often consider similar also. 5751 are cetainly a good tubes (try RCA commands, Syvania Gold Brand and GE 5* also) to look at further when correctly used / biased.
The Amperex US E88CC (6922) are certainly excellent tubes. Do look at the European 6922 however which I feel are better again, as are CCa, CV2493, E88CC-01s. However even the basic Mullard / Amperex EC88 / 6DJ8 from europe are excellent and often over looked. It is funny we started off with the cheapest Russian 6J5Ps and have made our way to Amperex 6922s! Don't you just love the LDs.
Thanks for your comments. I do in fact have my eye on a GE 5751. And while I would really like to get a Sylvania Gold Brand, the prices I am seeing are way too steep for me.
And I agree completely regarding basic ECC88 / 6DJ8. As a "bottom feeder", I managed to obtain Mullard, Amperex (BugleBoy, A-frame Orange Globe and red-label), Siemens (both ECC88 and PCC88), Reflector 6N23p, Tesla PCC88, and GE 6DJ8. Even though for the most part, these were all "well used" tubes, and cheap, I figured that they still have at least 100 hours life left in them, which would be enough for me to get a handle on their sound. And for sure, all of these are excellent tubes. However, in the end, the Amperex BugleBoy is the one I kept in my amp.
So it seemed logical to assume that I should probably seek out an Amperex 6922, either Holland or US made. Ultimately, my final decision was dictated by price. I was able to get these Amperex US tubes at a great price, and I grabbed them.
And of course, I will keep an eye out for great buys on other European 6922, CCa, CV2493, E88CC-01s. With patience, I am really hoping that I can find a great buy on a German-made premium Telefunken, Siemens or Valvo. But these tend to be very pricey, so I am prepared for a long wait.....