I would highly recommend the Sophia Electric if you DON'T want euphonic, warm but DO want balanced, accurate top to bottom sound with superb placement, staging and dynamic capabilities, I suspect due to the careful matching that you are paying for. The dynamics with this tube was quite a revelation to me in my Supratek Syrah pre-amp. These are the best I have heard and while not cheap at 200.00 a pair they are better than any of the NOS I have heard and own. I would also consider Ahendler's and the RCA GTA, GTB's at less cost. I haven't heard the Tung Sol round plates but am familiar with most of the above recommendations, my very favorite being the Sylvania brown base but these are certainly not equal to the Sophias IMHO. I have been touting these tubes since I purchased them a few months back and while there was initially a bit of harshness the stunning balance was evident right from the get go. They have now smoothed out and the highs are absolutely exquisite, no harshness but extended and airy.
Of ALL the tubes mentioned above, I would stay clear of the Ken-Rad black glass VT-231 unless you are looking for euphonic, inaccurate and for a lack of better description, phasey sound that seemingly expands the soundstage but to my ears is the worst 6sn7 I have personally heard. For the life of me I don't understand why this tube is ever in the conversation. I have a pair that test almost new, no gas emissions, shorts or any other issues that would explain to me why they might sound as they do, oh well, different strokes I suppose.
Of ALL the tubes mentioned above, I would stay clear of the Ken-Rad black glass VT-231 unless you are looking for euphonic, inaccurate and for a lack of better description, phasey sound that seemingly expands the soundstage but to my ears is the worst 6sn7 I have personally heard. For the life of me I don't understand why this tube is ever in the conversation. I have a pair that test almost new, no gas emissions, shorts or any other issues that would explain to me why they might sound as they do, oh well, different strokes I suppose.