New system/room, upgrade amp or preamp first?

Al, hopefully this pastes well, but the text of the Pre1 manual reads:

XLR Output Jacks for Left and
Right Channels
These outputs go to your power amplifier or
active crossover if it has XLR inputs. They
use the standard Male XLR pinout pattern of:
1 - Gnd
2 - Plus Signal
3 - Minus Signal

• RCA Output Jacks for Left and
Right Channels
These RCA outputs can be used instead of,
or in addition to, the main XLR outputs to your
power amplifier, active crossover, or
sub-woofer

Since neither my amp nor my sub accept balanced ins, it looks like your observation of using the adapters is probably still in play so I would likely just go with the speaker-level option for the subs. The subs operate in a very narrow window and are just there to troll the depths, so to say. I don't expect much if anything out of them above even 50 Hz, roughly.

The loop feature is listed as being useful for sources which have their own internal volume control, the preamp is bypassed entirely. Specifically useful as a HT-Bypass mode of operation.

Thanks Al!

I will throw this out there, just to get feedback - am I loony for thinking a simple single-ended Y out of the preamp would be doable until I (ideally) find a balanced amp so as to use enable both sets of outputs concurrently? Not dismissing the high-level input option, just curious.

04-24-15: Toddrhodes
I will throw this out there, just to get feedback - am I loony for thinking a simple single-ended Y out of the preamp would be doable until I (ideally) find a balanced amp so as to use enable both sets of outputs concurrently? Not dismissing the high-level input option, just curious.

Not a loony question at all. In fact, given the 50 ohm output impedance that is specified for the Pre1, I suspect that would work well, if perhaps not completely optimally. (I'm assuming that the sub can accept an input covering the full frequency range for at least one of the two positions of the switch I referred to earlier).

One thing that has to be considered with respect to that approach is the possibility that the combined input impedances of the sub and the power amp may be too low for the preamp to drive with good results. Particularly because the line-level (RCA) inputs of most powered subs tend to be low. There doesn't appear to be a spec on that for your BIC F-12 (the 8 ohm "input impedance" value that is indicated would be for its driver, not for its amp), but I wouldn't be surprised if it were in the 5K to 10K area. The combined parallel impedance of 5K and the 33K input impedance of your amp would be (5 x 33)/(5 + 33) = 4.3K. That would be too low for many preamps to drive with good sonic results, including some solid state preamps, most tube preamps, and probably all resistive-based passive preamps. But it shouldn't be much or any problem for the Pre1, given its 50 ohm output impedance.

A second issue that should be considered is the ability of the preamp to drive the combined capacitances of the cables to the main amp and to the sub, without perceptible rolloff of the upper treble resulting (the capacitance of the cable to the sub, as well as the capacitance of the cable to the main power amp, can potentially affect the high frequency content of the signal to the main power amp). The likelihood of that being a problem increases in proportion to the output impedance of the preamp, to the lengths of both of the cables, and to the capacitance per unit length of the particular cables. For most reasonable cable lengths and cable capacitances an output impedance of 50 ohms is low enough to make any such issue unlikely.

Finally, ground loop hum is a conceivable issue, but I suspect that the chances of that occurring with this configuration would not be particularly greater than in most other situations involving unbalanced interconnections to a sub.

Good luck. Regards,
-- Al

I've learned more about audio in general, and system considerations to a more specific degree today than any single day I can remember :) You are a very kind person to spread the knowledge you have to anyone willing to take it in. Thank you Al.