Budget preamp with quality volume control


Dear Audiogoners,

I used to be a firm believer that the signal path should be as short as possible and, as such, I have been using the two-channel system without a dedicated preamp. For a long period of time, I have relied on the digital attenuator in DAC for volume control, knowing the digital attenuator would compress the dynamic range of the sound. Therefore, I switch the volume control on DAC to the fixed mode, bypass the digital attenuation and use the unity gain knob in the back of the power amp for volume control. Depending on the music recording level, however, sometimes I need to turn the unity gain control way down to get proper sound level. This is particularly painful when I use the full-balance connection because of the double voltage gain.

In short, I am looking for a budgetary preamp with quality volume control that either has relay switch stepped control or precise potentiometer for left-right channel match to curb the issue. I try to summarize important (to me) performance catgories as best I can for various good sounding preamp I know (with or without headphone amp/dac) as shown below. It is found the Schiit Magnius happens to have the highest performance ratio. However, I am pretty sure that I likely miss other good performers due to my limited knowledge and would like to solicit for your inputs. Your kind assistance is appreciated.

 

lanx0003

The classic Adcom gfp 750 and Apt Holman recapped can still be found at a affordable price but Ayre k1x or Threshold Fet 10e would cost over $2k.  They must be the crown jewels top of the line back then.  Thanks for the recommendations.

I was looking through this post and thought - if I am only using the ONE digital source - would I really need a pre-amp at all? After all, a preamp deals with the switching of inputs (and I only have the one input) and also gain control but there's enough gain on a digital device anyway (broadly speaking).

I would need an attenuator - not a pre-amp (if you can distinguish the two) - so perhaps a high quality passive will do for me with no selector knob and only attenuator control. However, I would still need this single pot to be of high quality too - anyone know of something?

Ideally I would like a r/c attenuator if that's possible.

@chopandchange 

if I am only using the ONE digital source - would I really need a pre-amp at all?

That has been a question asked by many over the years.  Having enough voltage is one piece of the puzzle but impedance compatibility to drive the cables and power amplifier is another piece that is not addressed by simply putting an attenuator in the signal chain.   In short, many have found that preamps having a high'ish impedance input and low'ish impedance output to the power amplifiers seem to do a better job of preserving tonal qualities, dynamics, and drive, compared to using an attenuator alone.  A unity gain buffer following the attenuator can do the job fine in cases like yours where there is enough voltage coming out of the source.   

In-line attenutor is just a fixed output passive preamp as opposed to passive preamp with variable levels of attenuation. Not clear what "Indus" is but if Rothwell refers to their in-line attenuator, the output impedance is stated as 3750 ohms, a bit lower than the Schiit SYS (5k) but still high enough to reduce the impedance ratio (approx. 8.6) down below the desired 10. Note that the cable I was using is merely 12 inch long and my Parasound amp has a reasonably high 33k ohm input impedance. It is still likely the company’s in-line attenuator will impact on the sound quality as SYS does. As such, I have no longer considered the passive preamp or in-line attenutor option.

Some active (with gain) preamps also have attenuation function in addition to amplication, such as SPL Volume 2 (-4 dB) and some others. All the Schiit active preamps starts from a "amplication factor" (Schiit refers it as "gain") of 1 which gives no volume (dB) increase/decrease. The formula is 20*log(amplication factor). So amp. factor of 1 give 0 dB. When the amplication factor is less than 1, say, 0.63, change in volume is 20 log(0.63) = -4 dB (like SPL Volume 2 mentioned above) indicating that the preamp is actually performing attenuation. Those active preamps with gain is exactly what I am shooting for.