Audio Research amps - balanced & non

Hifigeek1...Before suggesting that Jensen signal transformers exhibit frequency roll off you really ought to check the specs. I know that high power audio output transformers exhibit roll off (usually corrected by ultralinear feedback) but these low level transformers are a different kettle of fish.

If you comment further, please report the specs you find.

As if these responses are not confusing enough, I'll add my own experiences with transformer coupling. I use a LF-frequency optimized Jensen Isomax between a balanced preamp and a sub plate amp-- which does a great job. On the other hand, the Jensen step-up transformers in my original BAT VK-P10 phono stage sounded mediocre. Similarly, in another high-gain balanced phono preamp, I found Cinemag step-ups were easily surpassed by gain achieved using matched bipolar transistors. Finally, the very expensive Audio Consulting Silver Rock step-ups that I use in the analog section of a modded CDP sound superb-- discernably better than other step ups I tried in that application.

I don't think generalizations about transformers hold up across applications.

Thank you all for your considered responses and suggestions.
Another option, of course, would be to replace the D-115 altogether with an SP-10-compatible amp such as VT 200SE or VM 220's that have singe-ended inputs (as it happens, each of these have both balanced/xlr and RCA inputs).

On that thread, I know the Ref 300 Mk II has balanced inputs only, but does the original Ref 300?
Any other Amp suggestions given I need 200wpc plus to feed MG 20.1's from an SP-10 and both phono & line/cd inputs?

Thanks!