SUT Advice - Which Ones Are The Best?

One of the nice things about SUT's is that they are passive devices and hardly subject to aging under normal use. And the 'technology' hasn't changed much, if at all. This means you can buy used without hardly any risk at all.

There are two 'big' choices you have to make:
- copper or silver wire for the transformers. Silver is obviously more expensive, but not necessarily better (very dependent on the cartridge)
- a dedicated unit for a specific impedance range or one with a selector switch to accomodate a wider variety of cartridges (usually choice between low impedance (typically 3-6 ohm) and high impedance (20-30). People usually prefer dedicated units, because the selectability involves extra switching.

There are many great ones out there, but a good choice for copper wired SUT is Entré ET-200 for 2-10 ohms (3,5 ohms ideal) and 30dB gain, designed by Matsudaira of My Sonic Lab. This is not a rare unit and regularly for sale around $600-700. The current My Sonic Lab SUT will not be much different except for the price.
A good choice for silver wired SUT is the Ortofon series for their '000' series MC's, the T-2000, 3000, 5000 and 7500. They all have the same specs (impedance range 3-6 ohms, 30dB gain), except T-2000 which has even higher gain to accomodate the ultra low output MC-2000. These nits can be found between $1000-1500 and are definitely worth it when compared to the 'adventurous' pricing of silver wired SUT's made today.

My own experience seems to suggest that things are not as simple as an active device being better than a passive one or vice versa. The interaction with the cartridge strongly determines the outcome.

This comes from extensive comparisons made with a Boulder 1008 phono amp. It has two inputs, so for this purpose one input was switched to MC and the other to MM, adding a SUT in the signal path. So basically I was comparing the MC gain stage of the 1008 with a SUT, all else equal. While the 1008 is not the best available, it's a competent solid state design without too many corners cut.

For me the outcome was undecided and simply depends on the cartridge. I've compared dozens of low impedance MC's with mixed results, but generally speaking Ortofon SPU, FR 7, Ikeda 9 and Miyabi seem to prefer a SUT in the signal path (with some preferring silver wire over copper wire and vice versa), while Ortofon A95, MC Anna and Transfiguration Proteus sounded much better with active amplification. Others were much less pronounced in their preference.

So what does this tell you? It all depends and you have to listen. That really helps, doesn't it?

@rauliruegas thanks for sharing. Both these units are highest quality and probably a 'step up' from the Ortofon T-3000 I'm using right now. But the Denon has only 21dB gain and not suitable for low impedance cartridges, so for me that's a no-no.
The AT-1000T gained my interest after I acquired the AT-1000MC, while the added feature of accomodating both low impedance (3 ohm) and high impedance (20/40dB) MC's simultanuously is also  interesting. Only 1000 made, so probably not easy to find at a reasonable price......

@rauliruegas my remark was based on the specs of AU-1000. If the information I've seen is correct, it has an impedance range between 10-40 ohms (which seems rather wide) and 21dB gain. At least on paper this doesn't sit well with many low impedance / low output cartridges, most of which are around 3 ohms impedance and 0.25 mV output (at least the ones I'm familiar with).

But apparently things can work out differently in practice, as your experience with the Etna SL suggests. Good for you!

@lewm I probably should have refrained from making that statement, but allow me to explain where it came from. Most low impedance, low output MC's I use (various Ortofon's including SPU, FR7, Ikeda 9, Miyabi, etc.) have between 0.2 and 0.3 mV output. My MM phono input stage has 40dB gain, so using a 20dB SUT (or 21 in the case of the Denon) would bring the total gain to 60dB. I have tried several SUT's with 20dB gain in my system (but obviously not this Denon) and in all cases and at the same volume level these low output MC's sound more alive and musical using a SUT with 30dB gain (like the Entré ET-200 and Ortofon T-3000 I'm using now).

The specified impedance is perhaps less significant, but I've tried some of these low impedance cartridges with SUT's that offer switching between low (usually 3 ohms) and high impedance (20-40dB). To my ears using the high impedance setting on low impedance MC's sounds much inferior to the 'correct' setting, of course with the appropriate correction of the volume control.

That's what I've learned from making these comparisons. So, when Denon specifies 21dB gain and 10-40 ohms impedance range for the AU-1000 model,  I'm inclined to think that this will not be the best choice for the cartridges I like. Perhaps the Denon flies in the face of that and I won't deny that possibility until I hear it myself.