Budget preamp with quality volume control

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.   

Thanks - this company thinks otherwise due to how short the cables for interconnects are etc ... read here:

http://www.rothwellaudioproducts.co.uk/html/the_truth_about_passive_pre-am.html

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.

Every passive attenuator company says the same thing, Goldpoint, the LDR folks (i.e., Lightspeed and Tortuga), manufacturers that put attenuators in their DACs like Metrum and Sonnet, and more.  Some say it louder than others.  Hattor/Khozmo offer both options, as well as op-amp or tube active stages to follow their passives, if desired.  I have tried more than a few passives, and currently own 5 different passive units, Goldpoint, Khozmo, Hattor, Endler (attenuators that mount to your amplifiers), and an icOn 4PRO autoformer.  I have also owned the Metrum Adagio DAC, with a lossless volume control.

The ONLY one of those passive solutions that IME preserves the tone and drive to the same level of an active preamp (or active buffer), regardless of how short the ICs are, is the icOn 4PRO AVC preamp, which uses Slagle autoformers.  The autoformers (a type of transformer) have the ability to decrease the output impedance while performing attenuation.  I really like the sound of the 4PRO but I also have a custom, higher quality, Khozmo dual mono passive unit that I use in front of a SMc Audio solid state unity gain buffer, which results in a quite low impedance signal going to my amplifiers.  I like the sound of the Khozmo/SMc buffer combination a little bit better than the icOn 4PRO.  The buffer does not provide gain (above unity), but with the buffer in the path following one of the  passives, I hear improvements in bass, dynamics, tone, and drive, over using any of the passives (except for the icOn) without the buffer.  The icOn 4PRO does not suffer the losses described above that I hear from the other passives.

All that said, only you can decide what type of sound you like, and what you hear in your own room with the equipment you have.  There are many here who like having a passive attenuator, and are happy with the sound.  In the end, any of us here can describe what has worked for us but "try it for yourself" is the only answer that really means anything.