The best preamp without a doubt..in my experience

^^ getting a preamp to jump through all those hoops would be a trick. Balanced and single-ended are inherently incompatible for starters.

to continue:

Adjusting the phono input impedance is something only needed if the phono circuit is unstable with RFI. So a better preamp really does not need adjusting input impedance as 47K is sufficient at least as far as LOMC cartridges are concerned.

The more geegaws you add, the less likely the unit will deliver the bacon...

But Ralph, I had a contrary experience. Properly adjusted gain provides the best resolution per desirable loudness. Each and every album you're listening to may have different recording levels and adjustable gain can give you advantage to compensate lack or excess of such

The more geegaws you add, the less likely the unit will deliver the bacon...

I believe that more 'geegaws' simply add-on to the manufacturing cost more than delivering or not delivering bacon.

Ralph, your statement that balanced and single-ended are incompatible reminds me that there is something I've been wondering: Not that you should necessarily be familiar with the designs of your competitors, but you often do seem to be! In the ARC Reference line stages, both RCA and XLR jacks fill the back panel. Unlike EAR products which also have both but provide balanced outputs via a transformer at the back end of a circuit, ARC claims to offer fully-balanced operation via the circuit itself, obviously on the XLR jacks only. Where, then, does the single-ended output come from?

The best preamp, to my ears, has been a dedicated ditto integrated into the DAC; that is to say, no separate hardware preamp in the traditional sense. With the power amp used (Belles SA-30) the matching to the DAC/preamp (SOtM sDP-1000) is very successful, and with not a flicker of the "anemic and drained/non-dynamic" sonic imprinting the DAC-direct solution has often been reported having. Matching obviously is paramount, but newer solutions of dedicated DAC/preamps have come a long way making named issue equal zilch, and thus matching is less of a problem. Volume controls also have come a long way via digital implementations these last years, though the one used in my SOtM DAC/preamp is in the analogue domain (digitally "actuated").

Much of the controversy/debate over whether to use a separate hardware preamp (when we disregard its necessity with turntable setups) or not (i.e. as integrated solutions with only a digital source) seem not to take fully into account how systems can be build from ground up via either one or the other; in my case I've intended the latter from the beginning as an outset that would then come to fruition, and as such the inclusion of separate preamps often tip the balance in my setup where very often a lack of transparency and oddly "flavored" signature sneaks into the sound. Very expensive preamps have sometime blurred which solution to choose, but where this has occurred my thought has always been that the expense would be better invested elsewhere.

Conversely where separate hardware preamps have been used as an outset in ones setup(s), it's easy to imagine how its negation could induce sonic alterations that stem from the balance of the setup as a whole, and thus might call for rigorous tweaking to come near ones preferred sonic balance sans preamp.

Bdp24, re your question, arcdb.ws provides schematics for a number of older ARC preamps. It appears that in cases where the internal signal path is balanced but outputs are provided on RCA as well as XLR connectors, the Ref 2 being an example (click on the schematic thumbnail at the bottom left of the page), the center pin of the RCA connector is wired directly to XLR pin 2, and is thereby provided with one of the two signals in the balanced signal pair.

Which means, of course, that if the two outputs are used simultaneously (perhaps to connect a powered sub to the RCA connector in addition to the main power amp being connected to the XLR connector), that a possibility arises for adverse sonic effects on the balanced signal path, and on the unbalanced signal path as well. Which may or may not be significant depending on the impedances that are involved, as well as the cable lengths and cable types.

Regards,
-- Al