Amplifier Recommendation

engie490

invalid wrote: »

The krell ksa 300s is not differential balanced it has balanced inputs and single ended inputs.

The FPB-300 has both kinds of inputs as well, so that is not an indicator of whether an amp is fully balanced.

I did go back and read over Stereophile's KSA-300S review and they did not mention "fully balanced", so I apologize for my error of memory. Mea culpa!

The Rotel RB1090 might not be a good match with the Freya in either of the passive modes. Stereophile measured the 1090's gain as 28 db unbalanced and 22 db balanced. The Freya+'s measured gain in either passive mode was -6 db unbalanced and 0 db balanced. So, either way you'll end up with 22db of gain from the combo, which is on the low side.

Were you using the balanced outputs from the Freya+ to the KAV250? Krell specifies 26.4 db for gain, but doesn't note a difference for unbalanced or balanced connections.

Overall, I would want the system gain to be at least 30 db. Thus, I would probably opt to use the Freya's tube section with the RB1090, which would put the combined gain around 34 db with either connection.

Of course, YMMV.

invalid

@engie490 I wasn't trying to say that having balanced and single ended inputs was an indication of it being differentially balanced. I was just stating that having balanced inputs doesn't necessarily mean both channels don't share a common ground. I have used my krell KSA 300s amp for 7 years with my sda2a's.

crashb4

engie490 wrote: »

invalid wrote: »

The krell ksa 300s is not differential balanced it has balanced inputs and single ended inputs.

The FPB-300 has both kinds of inputs as well, so that is not an indicator of whether an amp is fully balanced.

I did go back and read over Stereophile's KSA-300S review and they did not mention "fully balanced", so I apologize for my error of memory. Mea culpa!

The Rotel RB1090 might not be a good match with the Freya in either of the passive modes. Stereophile measured the 1090's gain as 28 db unbalanced and 22 db balanced. The Freya+'s measured gain in either passive mode was -6 db unbalanced and 0 db balanced. So, either way you'll end up with 22db of gain from the combo, which is on the low side.

Were you using the balanced outputs from the Freya+ to the KAV250? Krell specifies 26.4 db for gain, but doesn't note a difference for unbalanced or balanced connections.

Overall, I would want the system gain to be at least 30 db. Thus, I would probably opt to use the Freya's tube section with the RB1090, which would put the combined gain around 34 db with either connection.

Of course, YMMV.

I used the balanced output with the Krell. Just hooked up the 1090. Definitely needs the tube stage. The 1090 will run single ended from the Freya+. The Rotel balanced inputs are not true balanced. This way I will skip the conversion step.

"the Rotel is what some call "pseudo-balanced," in that the circuitry itself is unbalanced; balanced input signals are converted to unbalanced internally".

Thank you so much for the information. I am certainly not an electrical engineer, and there are gaps in my research due to time constraints. I appreciate every one of you guys for helping. I forgot how awesome this group is.

crashb4

Had a quick listen at modest volume before the house went to bed. Reference material for me is Pink Floyd, Shine on You Crazy Diamond Part VI - IX. Some delicate passages as well as some deep bass. Tube section enabled with older RCA black base 6SN7 tubes. I have to say, it sounds like a vail has been lifted from the front of the speakers. The Krell was actually a bit muddy by comparison, with or without the tubes. I don't know if it is the dampening factor of 1,000, But the bass is much more controlled and there is more detail. The Krell is "colored" in the low end. Not nearly as transparent. These are just initial impressions. Things may go sideways under more scrutiny, but the sound of the Rotel is very familiar, having owned one previously. I like what I hear so far. Worth the roll of the dice.

Once again. Thank you all for taking the time to respond, and supplying valuable information. I am indebted.