When is it time to consider adding a SUT?

Doesn’t the REF 3 already employ an SUT when running through their MC input. I think at times it’s overlooked, but most tube phono stages have built in SUT’s. Manley, Aesthetix, and as all who frequent A-gon know, Atma-Sphere, do not use an SUT. IME, 68 db should drive a .3mv Benz. Not an easy task for a tube stage without an SUT, but 68db should work, pending it's quiet enough for you. I drove a  Benz Ruby 3 with a Lamm LP2, and the 57.5 db gain was not quite enough.... Cheers -Don

The ARC Reference Phono 3, like the Reference Phono 2, has a FET front end instead of a SUT. Mine has plenty of gain to run a Benz LPS into an Aesthetix Calypso.

The LPS is not really a great candidate for an SUT because of its 38-ohm internal resistance (DCR). At .36 mV, you’d likely want to use a 1:15 SUT, which would present an impedance of 209 ohms to the cartridge. That’s pretty low, when you think rule of thumb is 10-25 x DCR (I prefer 25x usually). 1:10 would create a better impedance match at 470 ohms but the gain might be sub-optimal.

I have an older Ebony L at .26 mV and DCR of 3.5 and I use an SUT of 1:20. It sounds good but the loading is a touch high at 118 to the cartridge, accentuating the top a bit. The newer Ebony L has a DCR of 5, which is better for 1:20.

The only Benz that is a truly great match for an SUT is the Ebony TR, which is designed for use with one. With a DCR of 1 ohm and output of 0.1 mV, it should be pretty ideal for an SUT of 1:40.

Thank you for your insight. It is very valuable. My question was not so much about there being enough gain but would the addition of a SUT improve the end to end performance of my set-up and wrm57 indicates that it wont.

I'll report back when it arrives to comment on the end to end performance.   

don't sully yr ref2 with a sut !
it should have more than enough gain for the benz.
keeping the signal path simple will give you the best sound.
;)