Hi Jim,
He informed me that "Line 3" of the Sphinx integrated is an input, not an output. There is an area on the back of the Rogue Sphinx sectioned off that has a variable and fixed output The "variable" output is the one he recommended for hooking up the BAT VK-200 amp
Yes, that is what I had said in
one of your other recent threads.
In this lost e-mail, I mentioned that I had called Rogue, and was told by one of the techs that variable( pre-out) output runs through an "op-amp", and not the "tubed" section of the Sphinx pre-amp stage. He also noted the sound may not be quite as good, with a minimal loss of sound quality. O’Brien more or less confirmed the same fact to me in today’s conversation I mentioned in my e-mail that unless I am wrong the so-called pre-out was not a true or standard pre-out like the one in the Creek 5350SE Classic which I owned about 7 years ago, using it with a pair of Red Dragon M-500 Class D mono block amps.
However, I don’t know if op-amps are a standard design component for pre-amp outs on integrated amps in which you can separate the amp from the pre-amp stage. O’Brien claims that using variable pre-out on the Sphinx will still allow control of volume and other features on the integrated amp
Yes, we had discussed that in your other thread I linked to above. The hope and expectation, that seems reasonably consistent with the comments by Mark and by the Rogue tech you spoke with previously, is that the implementation of the Sphinx’s variable pre-out, while less than ideal, should be good enough to allow you to benefit from the power amp upgrade, and provide you with reasonably good results in the near term. Note the word "minimal" in the comment by the Rogue tech, with Mark apparently having commented similarly.
I don’t think it would be meaningful to think of the op amp implementation of that output as being "true or standard" or not "true or standard." It is simply one way of implementing a pre-out, and I’d feel certain that approach is not unique to Rogue.
I think I am somewhat back to Square One because one of benefits of XLR to XLR interconnects was the reduction of noise. I did buy the BAT VK-200 amp The deal was too good to turn down.
I don’t think you went wrong, by any means. The noise reduction that can be provided by a balanced interface (and also its reduced susceptibility to ground loop issues, that may cause high frequency noise as well as low frequency hum), is probably not a significant issue in the majority of home audio setups. That potential benefit can be expected in most cases to be overshadowed by differences in the quality of the particular component designs. And specifically in the case of many components that are not "fully balanced" but provide balanced interfaces, that potential benefit can often be outweighed by implementation of the balanced interface that is sonically compromised in the interest of keeping costs down. Such as by the use of a cheap op amp to generate one of the two signals in the balanced signal pair, by inverting the other one.
I would expect an Ayre or BAT fully balanced preamp to be a great choice, if you can find one at a suitable price point and in top condition. That’s a big "if," of course. But within your price range a preamp having an unbalanced internal signal path while providing XLR inputs and outputs might turn out to be easier to find and (depending on the specific design) a comparably satisfactory choice.
Good luck. Best regards,
-- Al
