Modwright LS 36.5 or BAT VK-51SE

Roor- When you gonna upgrade those speakers? I'd do that before anything else.

As far as the preamp goes. I've got a Modwright SWL 9.0 and absolutely love it with my Pass Labs amp. Mine is the model below the 36.5 you are considering. I enjoy the flexibility to roll tubes and the weight and body it adds is superb.

Erndog: Yes, I want to upgrade speakers as well, and am negotiating on a pair of preowned Daedalus Ulysses.

Tvad: Pauls's response regarding the balanced option and impedance was

"No, I've never heard a line transformer that I liked, even spent lots of money trying to get some made. We use a resistor pull-down xlr. I think we've sold a Dude to a Pass owner, what's the input impedance? Dude is happy with 25K or more load. Lower, there might be some bandwidth loss, might be more of a situation on paper than in actual use, though. Thanks,Paul"

The input impedance on my XA-60.5's is 30k balanced and 15k unbalanced?

I'm not certain these will be compatible? Any thoughts, as I don't know much about impedance and proper matching?

Will I be ok if I used the balanced input on my amps connected with a resistor pull down xlr on the dude?

Thanks,

Greg

Roor, since the output impedance spec of the Dude is not provided, it seems to be a situation where you'd have to hear the preamp in your system to decide if it matches or not. You'd want to be listening for rolled-off highs. I don't know what a resistor pull-down XLR is.

The BAT VK-51SE was tested by Stereophile, and the output impedance was measured at 410 ohms (200 ohms spec'd by BAT), and rising to 4700 ohms at 20K. John Atkinson writes:

"This will not be an issue with components having high input impedances, such as BAT's own power amplifiers, but it does mean prematurely rolled-off low frequencies with low load impedances (fig.1), such as those offered by some solid-state amplifiers."

The measurements are here.

The Modwright preamp has a factory spec'd output impedance of 110 ohms, which is quite low. However, it has not been measured by Stereophile, so the question of how high the output impedance rises into high frequencies is unknown.

BTW...I once owned a Lamm L2 Reference preamp which I used with my XA-60.5 amps. I thought this match was very good. It took quite a while comparing it to the SMc Audio VRE-1 to decide to sell the Lamm. I imagine some listeners might even prefer the Lamm.

The L2 Reference runs about $6000 used. I think I bought (and sold) mine for less than that.

Tvad: Was there any hiss or noise with the L2 Reference with the Pass Labs XA-60.5's?

I've read several posts where the Lamm L2 reference hisses loudly with just about every other amp besides their own, and Lamm says it's "normal". It's driven people crazy that tried to fix the problem with no luck, so it sounds like a risky move. I'm leaning towards the Modwright LS 36.5 at this point or possibly that with seperate dual mono power supply.