Balanced and Unbalanced outputs simultaneously

I have a question regarding balanced and unbalanced outputs. I have a Benchmark DAC 1 that has both unbalanced and balanced outputs. Currently I am using the unbalanced (RCA) outputs to my trusty tubed pre amp and then from there to the RCA inputs on my Bryston 4B ST. It sounds great and I love the fact that I can roll in different old tubes to change the character of the sound. However I want the best of both worlds on the pre amp side and was wondering if I could use the balanced outputs of the Benchmark to a solid state pre amp and then balanced outputs from the pre amp to the Bryston. Then all I would need to do is switch the input mode on the Bryton to go from balanced to unbalanced and thus from a tubed pre amp world to solid state. My questions are does the Benchmark provide a single to both outputs simultaneously or does plugging in a balanced cable disengage the unbalanced outs? Also can anyone see a problem with hooking things up this way? (I don't want to blow anything out but can't really see how that could happen since I suspect that the toggle switch on the Bryston would prevent that.

Any thoughts?? Doug
Dougwhitesell, I have Benchmark DAC1 and don't know of any switches. From what I can see signal splits after D/A chip and goes to separate op-amps for XLR and RCA outputs. RCA outputs can be calibrated with multiturn trimpots while XLR outputs are set by internal jumpers. I find sound at 0dB position most vivid in spite of very short (0.5m) and very low capacitance (5pF/ft) IC. It was also noticed in few reviews.
Ok so both outputs then are active and amped simultaneously right? I thought that maybe when a balanced cable is plugged in that it may disengage the RCA outs. I'm not real knowledgable about the electronics so thanks for your resposne.
I don't see any problems in this case, except that my instinct would be to avoid changing the position of the amp's input select switch while the amp is powered up.

I'm sure Kijanki is speaking knowledgeably and accurately about the Benchmark. With respect to the amp input, as can be seen in the schematic (page 16 of this large pdf download), the input select switch entirely removes the unselected input from the signal path, so what you are proposing should work fine. In some other designs the RCA input is connected directly together with the "hot" signal on XLR pin 2, and the switch shorts the "cold" signal on XLR pin 3 to ground when the RCA input is selected. If the design had been like that I would not recommend doing what you are proposing, for several different reasons.

-- Al
Dougwhitesell, This is excerpt from Steven Stone Benchmark DAC1 October 2007 review in "Enjoy the Music".

"Since it has both XLR balanced and RCA single-ended outputs, the DAC1 can be hooked up to a stereo amp through the XLR connections and to a subwoofer through the unbalanced RCA connections. That's just how I used it in my desktop system."
Hey thanks so much gentlemen for your prompt and informative responses. I would surely have the amp (and all components) powered down before switching anything. Almarg thanks for the link to the schematic and thanks Kijanki for the Benchmark info. I think i will give this a go and purchase a solid state pre amp.

Thanks again. Doug