SOtM sPS-500

First, the sPS-500 goes up to 19 volts, which may suit a larger array of equipment (like the Gigabyte BRIX and other servers). They’re similar in size, but the SR4 is much heavier – must be that toroidal transformer. Both of these supplies are tonally similar (a good thing), very clear, musical, and smooth sounding. As far as sound, the SR4 is immediately more dimensional, more textured, more nuanced, with a tighter low-end. The sound just reaches further into the room with more shape and presence.

However, most will grab the SOtM sPS-500 for its power output (it has more continuous power) and flexibility, especially in powering multiple devices or larger devices. I currently have one powering both my modem and router. A extremely versatile and great sounding power supply I’ll be keeping around.

UpTone Audio UltraCap LPS-1

Unfortunately, I couldn’t get the new and improved LPS-1.2 in for this review. The LPS-1 is the much smaller (and much sexier) power supply. Its input is also DC from a MeanWell SMPS. I didn’t try using a better power cord on the MeanWell, so this could’ve tipped the scale in some categories.

The LPS-1 is on the brighter side of neutral but is very resolving, transparent, and very quiet. However, like the SOtM sPS-500, the LPS-1 can’t compete on depth when compared to the SR4. The SR4 has a calmer presentation, more dynamic solidity (especially on the low-end), and just images tighter. The SR4 also has more contoured and fuller outlines, acoustic cues, and soundscape localizations. The LPS-1 is slightly diffused but airy and spacious sounding. In some ways, the LPS-1 even dug up more low-level details over the SR4 – albeit with a more “energetic” sound.

Paul Hynes SR7

The aim of the SR4 is to get affordable performance from a smaller package. Let’s see how close it got.

Most of my SR4 vs SR7 testing was done with the SOtM sCLK-OCX10 and SOtM tX-USBultra. This particular SR7MR2XL (dual 12V rails) has internal annealed silver leads.

The SR7 is a custom manufactured mains transformer with up to 500VA rating depending on the overall rail requirements. The custom manufactured mains transformers use oversized grain orientated silicon steel cores and are wound to avoid core saturation in use and to operate quietly both electrically and mechanically. Schottky Barrier rectifiers are used throughout the range, as they do not generate reverse recovery transients and their associated harmonic distortions.


I use Panasonic FC and FM capacitors. Typically for a 12v rail the 3A module will use 6,600 uf and the 6A and 10A modules would have additional capacitance to keep ripple voltage on the raw supply at reasonable levels at full load and also to ensure plenty of reserve regarding ripple current rating.


The 3 wire weave is to provide a distributed capacitance along the lead which helps to counter inductance and maintain a low impedance at high frequencies. The third wire is connected to the power supply chassis only to help dump and RFI pickup into the chassis ground.

Although the SR4 conquered those before him – he’ll still have to bow down to big daddy SR7. He is a mere prince in the presence of a king. I would say the SR4 has 80% of the genetic makeup of the SR7, but the SR7 is still an appreciable step up in performance – worthy of every penny IMO.

The SR7:

  • is even smoother and has a larger sonic image. The SR4 sound every so slightly rougher and smaller in comparison.
  • has truer timbre paired with higher resolution. Tough to get both without making it sound analytical.
  • sounds more musical in gradients and transients, you hear more of how the music glides and the weight involved in carrying the sound.
  • is more solid and less diffused vs the SR4. Can’t really tell unless you A/B, but it’s noticeable.
  • has more accurate tonal density. There’s a physical weight to the sound which brings it much much closer to something with more lifelike continuity.
  • is more dynamic and authoritative, especially in the bass region.
  • relays more texture and speed.
  • has a more accurate midrange – vocals are oh so beautiful.

In comparison to the SR4, the SR7 is more solid and refined across the board. Objective listening converts to an enjoyable session every time with this power supply. Natural sounding soundscape with a velvety smoothness I’ve never encountered from my system. There’s no sense of digital grain or harshness and it has the lowest noise floor of the bunch. There’s something very special about the precision and articulation of the SR7.

I know I gave the title to the SR4, but the truth is, the Paul Hynes SR7 is unequivocally the best power supply an audiophile could buy today.

Why does the SR7 sound better than the SR4, even when they have similar parts? According to Paul, this is due to layout and a few other things he’s (understandably) keeping secret.

Where can I get an SR7?  Unfortunately, you’ll have a patience of a thousand saints. Unlike the SR4, SR7s are custom builds that require a deposit and take over eight months to deliver – and custom orders are currently halted. This comparison wasn’t without reason, however. Paul Hynes is currently working with a contract manufacturing company (CMC) in the UK to remove this bottleneck. This should enable larger batches of SR4s and also put SR7s back in production.

Cross your fingers and pray to the audiophile Gods. Either that, or we’ll just have to clone Paul Hynes.