DAC voltage as pre-amp and relation to SPL

[Gerryh]

Hi all,

I've got a question relating to the Vrms output of a dac used as a pre-amp into a power amp, and its relationship to SPL. As an example with a dac that can output say 4vrms from an XLR out to a power amp - would a dac that can output say 5 or higher like some of the Benchmark/RME dac's allow for a higher SPL - with the same power amp?

The reason I'm curious is that I have essentially capped the SPL at about 92 db peak and about 85-88 average (DB c weighted) in my system due to volume levelling and DSP used in Roon. That would be with my dac volume set at max and gain on my power amp set at mid point ( mid-point eliminates tweeter hiss - at max gain there is a bit of detectible hiss close to the speaker).

My signal chain is this:
Roon -> ROCK core - > Cambridge CXNv2 dac/preamp via ethernet -> Crown XLS 2002 via XLR -> Kef R700 + Svs Sb-2000 subwoofer

The DSP is a convolution filter that reduces volume by about 6db cutting peaks, and I use volume levelling on playlists to avoid the inevitable grab for the remote when a particularly loud song comes on. Volume drops vary by song but can be -3 to -7 or so db. So in total can be 10-14+ db which, in its absence. would probably allow for volumes in the 95-98 db range and 104 db peak without changing gain on the amp. Which I guess would probably be a lot closer to what the system could play at.

So is there a way to increase SPL by increasing the voltage out of the dac? Or adding a separate pre-amp? Or would the solution be to bump up the gain on the amp and/or eliminate the volume levelling/DSP in Roon?

Thanks in advance.

Gerry

 

[Blumlein 88]

Simplest fix if you don't hear hiss where you listen is to raise the gain on the power amps setting. Hearing hiss right at the speaker if you listen several feet away and don't hear it makes no difference. If you can't hear it from the listening position it isn't there audibly.

It also is true using a DAC with higher maximum output would give you what you want. You'll need twice the voltage to make up 6 db and 4 times the voltage for 12 db.

 

[Wayne A. Pflughaupt]

Not getting the problem. Are you saying that after the DSP drops the source signal level, you can’t get enough volume from the system?

Regards,
Wayne A. Pflughaupt

 

[Gerryh]

@Wayne A. Pflughaupt - Yes that's correct.
@Blumlein 88 - Thanks. I guess I am a bit lucky in that the amp has adjustable gain which will help a bit. Otherwise it doesn't sound like many dac's will have that type of voltage to make up the lower source level. Would a pre-amp help?

G

 

[Blumlein 88]

Thinking further yes a preamp would fix your problems. You don't really need 16 volts output. You just need some gain to make up what the dsp is costing you. So any preamp with a few volts out should do it. Just make sure it has at least 12 db of gain.

 

[gvl]

Maybe a DAC that can output more voltage, eg RME ADI-2 or Benchmark.