> Glensound only has a transformer on the output, so that should make it sound a tad more transparent than the MP-1, but also not as warm sounding.
I would like as politely as possible to question that assumption. I know this is hard for some people to accept, but good audio transformers in appropriate circuits can be sonically transparent when they aren't being overdriven. That is, a human listener could not tell whether they were in a circuit or not, when listening to any actual program material through them (or test tones, for that matter).
But when transformers aren't sonically transparent--for whatever the reason may be, including that the circuit designer may have chosen their characteristics for a certain sonic effect--then their sonic effect can be to contribute "warmth" or it can equally well be a range of other possibilities.
If a person is just browsing spec sheets and not actually testing the specific preamps, either by listening for their sound quality or even measuring their performance with sine waves on a test bench, then no reliable predictions can be made at all about the likely sonic effect of either having a transformer or of not having one.
Again, my apologies to anyone whose views on this subject are incorrect <g>.
My opinion is not at all technical from a bench/datasheet perspective, so please accept my apology if my statement was in any way implying that.
My take is more along the lines of musicians' "tune by ear" method, where a person who has good pitch does not really need an electronic tuner for their guitar, for example. I have tried and listened to enough portable preamps over the last 25 years to render a personal opinion that the MP-1 has a "warm" sound that I attributed to the transformers.
I have a pair of Shure FP11 mono preamps that I used alot back in the '90s that I also found to be "warm" sounding, which I attributed again, evidently incorrectly, to be a characteristic of the transformers. I know I like the sound of preamps with transformers better, and I guess I have no scientific reason to do so, just like I have no scientific reason to explain the music I like to record with them.