Budget preamp with quality volume control

As many of you know, the basic relationship between the signal transfer (in terms of voltage) ratio to impedance between output (source) and input (load) is

Vi / Vo = Ri / (Ri+Ro+cable impedance), where V = voltage and R = impdenace

For a standard 75 ohms interconnect cable, without loss of generality, if your preamp output imp. is roughly comparable to the cable impedance, Vi / Vo = Ri / (Ri+2Ro). As a rule of thumb, it is desirable to have Ri is at least 10 times higher than Ro. The corresponding Vi / Vo = 83%. There will be 17% signal loss, acceptable (see below for the coveat) but not ideal. If Ri is 100 times Ro, the Vi / Vo ratio will be 98%, only 2% signal loss and will be deemed ideal.

In @jpasko01 case, i.e., Freya -> Bryston 4B3, Ri = 100 Ro and therefore the signal loss is only 2%. The pariing should work like charm. In the case of a passive preamp SYS (Ro = 5000 ohms) into my Parasound A23 (Ri = 33k ohms) where the ratio is merely 6.6, the Vi / Vo = 33000 / (33000+5000+75) = 87%. This 13% signal loss is significant enough to cause noticeable sound degradation that I heard. This demonstrates that the ratio of 10 is just a rule of thumb, the ratio should be as high as possible like 100 to be ideal. Since I have not seen a passive preamp impedance is lower than 5k ohms, practically only the active preamp is possible to achieve an ideal impedance match.

@jpasko01 Two things regarding the impedance matching with the Freya, if you are using unbalanced, you are fine, however output impedance is 600 ohms for balanced. More importantly, read John Atkinson’s analysis in the Stereophile review. Again, regarding balanced connections, but he suggests anything under 10Kohm input impedance may not do well with the Freya. My amp is right at 10K, and seems fine. 

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.

@lanx0003, The Wyred 4 Sound mPRE preamp priced at $1100 has both active and passive topology. The volume control is a switched resistor array (based on the $2000 Wyred 4 Sound STP-SE preamp) and it paired with my Clayton Audio M200 stereo amplifier, a full loom of 聖 Hijiri Nagomi interconnects the synergy is there in spades and my modest rig sings. At it’s $1100 price point it also comes with a remote.

Check it out: https://wyred4sound.com/products/mpre Here's a review from sixmoons.com:https://www.6moons.com/audioreviews/wyred8/1.html that will more completely explain the specs of the Wyred 4 Sound mPRE preamp.

@zlone is correct. The reasons, as shown in the "measurement" section, are (for Freya)

The active balanced output impedance was the same with or without the tube stage operating. It was close to 810 ohms at 1kHz and 20kHz but increased to 6900 ohms at 20Hz. The buffered unbalanced output impedance at 1kHz and 20kHz was inconsequentially higher than the specified 75 ohms, at 90 ohms. However, it rose to 3100 ohms at the bottom of the audioband. With the tube stage operating, the unbalanced output impedance was 3267 ohms at 20Hz and 1200 ohms at 1kHz and 20kHz.

Especially on the low ends from either output, the output impedances are much higher than the specified 75 ohm.  Frequency dependent impedance, interesting, needs to be watched for.  Lean something each day.  Thank you.

@tyray Thank you.  I also like what I see from this review. How do you like its DAC?  In particular, how are the soundstage width and depth?

https://positive-feedback.com/Issue72/wyred_mpre.htm