To preamp or not to preamp

[PAR (Pete)]

@Donald_D

for the same “loudness” the volume on the Rossini to be set at -42.5dB

This suggests that you are using the line voltage output too high. The idea of it being variable is so that you can set a combination of line output, amplifier input sensitivity , speaker sensitivity etc, so that the Rossini volume control may be set at at reasonable level that offers a subjectively realistic range of control. BTW, -42dbfs is way below the lowest suggested by dCS.

You may still prefer the Quest with a more appropriate line voltage/volume setting for all I know but the comparison would be more meaningful.

[Donald_D]

Good point! I redid the comparison with 2V out from the Rossini directly to the speakers. I used an SPL meter on the iPhone (I went by ear before) from the exact same spot, and measured “Chicago” by Oscar Peterson (made screenshots at 2:20 and at 3:00). The volume on the Rossini had to be set to -30dB to match the volume going via the Quest at +18 with the Rossini out 6V at 0.0dB.

Rossini out 2V direct at -30dB @2:20

Rossini out 2V direct at -30dB @3:00

Rossini out 6V at 0.0dB via Quest at +18 @2:20

Rossini out 6V at 0.0dB via Quest at +18 @3:00

Going direct with 2V out and -30dB on the Rossini definitely sounds better than going direct with 6V out and -42.5dB, and, I’d say, Oscar Peterson’s track sounds nice. With the Quest the soundstage is not only slightly wider but also deeper. The presentation is holographic. One could get the initial impression when the music starts that it’s at the expense of texture, but there is definitely better delineation of detail, more clarity/transparency. And most importantly, the sound is very musical and very engaging. One wants to get up and dance to Oscar Peterson with 6V out and the Quest in-between the Rossini and the speakers. It sounds amazing. I wish, people could hear it.

[Urbanluthier]

I’ve tried to maximize the performance of my Bartok direct over the past couple of years and my current thinking is this…

6V and 2V are the outputs to use as .6 and .2 are digitally attenuated off of 6V and 2V. Use 6V - if you can listen between 0dB and -10dB. if not, use the 2V setting as long as you can stay above -30dB. If you drop below -30dB, consider a pre amp.

[Donald_D]

@Urbanluthier

If you drop below -30dB, consider a pre amp.

I posted almost at the same time.

[Urbanluthier]

I struggled with this as well and found using a dB metre like you, that the 2V setting was the most dynamic given that I listen between -15 dB and 0dB at 2V. On rare occasions, I go to 6V if the recording I’m listening to was recorded at a low level.

I’m guessing that I get about 3dB extra in dynamic range listening at 2V in the range I’m use to rather than going with 6V and dropping 10dB lower.

I know using the mic in an iPhone as a metre isn’t supper accurate, but it seems to confirm what I’m hearing.

I’m fairly certain I got the idea from @Anupc who did a similar test with his Vivaldi

[Donald_D]

@James

Level matching is less easy to dismiss. If the amplifier were very sensitive, to the extent that our volume control was having to be backed off by 30dB or more, there might be a case for inserting a preamp. In all other circumstances, our digital volume control will introduce less crosstalk, noise, distortion and gain and frequency response errors than a preamp. In the vast majority of cases however, lowering the volume control by more than 30dB would suggest a gain issue elsewhere in the system which would need to be addressed.

James answered why I need a preamp in my setup. The “gain issue” is this iTRON technology in the speakers, I guess. I’m super happy with them, though, because they sound particularly good at low volume, and they are engineered to do so according to the marketing material. It’s just that the Quest adds substantially to the overall cost of the system.