New Cable Help-Balanced or Single Ended

If the source DAC has balanced outputs and the DR25 has balanced circuits it will sound much better, IMHO, especially if you are in a "noise rich" environment. I'm not, and it sounds better than SE. IMHO. The bablnced input also gives more gain and has a better impedence profile on the 750.

I'm not completely certain on this, but I don't think the Adcom design is a balanced one. It may have balanced connectors, but the internal circuitry I believe is running single ended. If that is correct, I don't think you will have an appreciable difference on the connection from the CD player (or DAC in this case) to the 750, unless perhaps the DAC is a truly balanced design. Some companies, such as BAT use balanced circuit design throughout the product--for these products you should always use balanced cables when possible. However, in your case, from the pre-amp to the amp is a little different issue, particularly if you are using long interconnects or you are in a noisy (RF and EMI) area. If either of these is the case then I would recommend balanced. If it is not the case, then it's going to be tough to know for sure without trying.

Additional Information:
Thanks for your responses so far. I did some additional checking and the Adcom GFP750 is supposed to have true differential balanced circuitry. Nelson Pass stated "the performance is best when it is run balanced." The DAC 3.0 is fully balanced so DAC to preamp should be fine without any balanced to unbalanced circuit changes. I think the DR25 may be the weak link. I cannot find any literature whether it uses fully balanced circuitry or not. I have read posts both ways. It is an older amp, but still quite good, and was originally $4000. I would think they would have not cut corners on an item in that cost range, but even the owners manual is not clear on whether the circuitry is fully balanced. I am also worried about a thinness in the sound some have talked about when running balanced compared to singled ended. I have no noise issues and I am not running long interconnects (1 meter) so these are not issues and I could go either way.

The DR25 is a very good amplifier. Does the DR25 have balanced (XLR) inputs? You can also run all balanced into the preamp, then simply RCA out of the preamp. The benefit here is that you get 6db greater gain before you hit the input circuitry of the amp, as well as running the other components balanced, taking advantage of differential circuits. There may also be some i/o impedance benfits. As far as thinness goes, it must be the cables or some other cause. All things being equal, I have never noticed a thinness in the sound of a balanced set up. Contact me by email if you want to discuss further.

I have a Rowland Model 2 amp I use with an Adcom GFP 750 pre amp. Both are fully balanced. The usual question is do you have an unacceptable noise floor? The noise floor in my system is not an issue. I use the components with balanced cable because they're balanced pieces - I want to utilize them to their fullest.
I also have an Aleph pre amp & Aleph amps I use single ended - the noise floor is also not an issue with them.
(I do have what I consider very good power line coditioning, I believe it does make a big difference).
Do you have a local dealer who will work with you? Try to borrow some definitely broken in cables of the same brand or price piont (balanced & unbalanced) & audition them for a few days....

P.S. Some cable companies will simply re-terminate single ended cable with XLR connectors, these are not what you want! If you have a doubt, simply check all 3 pins for continuity.