[Satanzilla]

I recently purchased an SP-2 (1.7 upgraded) preamp which I am using in conjunction with an Oppo 105 as my AV receiver.  First let me say its an amazing pair (well, trio with the Harmony remote). I have never heard such gorgeous sound, detail, soundstage, and especially bass and bass detail like this from my KEF LS50s.  I finally feel like they live up to the hype and then some.

So the issue I am having is that the gain levels are so different between its own processing outputs and the 2 channel bypass output, that I get blasted whenever I switch to 2 Channel Bypass. The gain is so high I barely have the Bryson's volume up off zero before it's at full listening level.  I also think this this over-preamplification is adding distortion to what would otherwise be the superior sounding output. My current fix is to have the Oppo's volume adjusted down to 80% instead of a fixed output but that makes the Brystons 6 channel bypass output lower than the standard outputs, which I like to switch between for different material.  Otherwise the the standard and 6 channel would basically match, which is preferable. 

So now the 2 channel bypass paired with the Oppo's dedicated 2 channel higher quality (higher gain?) unbalanced outputs are tamped down 20% but still much much louder than the other outputs. I tried adjusting the SP2 speaker levels down for that input, but that doesn't seem to apply to 2 channel bypass. Is there something I am missing here?  Is there something wrong with my SP2? Or is there something I can yet do within the Brystons per input settings to adjust gain in 2 channel bypass?  Or do I have to add something inline to lower the output?  Anyone dealt with this?  Suggestions?

[servingko]

Have you tried changing the input sensitivity on the 4b?  The trim levels do not work in bypass mode on the SP 1/1.7/2 and having owned essentially the same setup, I preferred the sound of the dacs in the 105 to the SP in most cases but the bass was tighter and deeper with the SP.  You can pad the 105 output down into the 60-70 range without truncating bits at a level you would be able to hear.

In the end I preferred the sound of the 105 direct to my amps and pulled the SP from the mix.  As long as the amp input impedance is in the 47k or higher range on single ended inputs you are fine driving it direct and the 4B would fit this requirement.  I would love a purely analogue multi channel preamp that was just a master volume control without all the other circuitry in the SP series.  I used 3 BP6 preamps for a while but it was too cumbersome and had high fiddle factor.

If the suggestions above fail, you can also buy line level attenuators that would pad down the output but this places additional circuitry in the path.  They come in ranges of down 3,6,9,12 db but an impedance mismatch can impact frequency levels.

[brucek]

Satanzilla, I have the same SP-2 (1.7 upgraded) and yes the analog bypass is a bit hotter than the DSP modes. Certainly the specs for the SP-2 confirm this, revealing Output Level: 8 Vrms (16 Vrms Balanced) in DSP Modes; 10 Vrms (20Vrms Balanced) in Bypass Mode.

No, there's nothing wrong with your unit, you simply have an input analog signal that's too high. You may need to pad the analog input signal. The specs show the input level at 4 Vrms in Bypass Mode. Check the specs on your source equipment. You may need to reduce it through attenuation.

brucek