Atma-Sphere in CO?

I've now gotten a good demo with the M-60 (it came with a nice set of VT-321s, including RCA smoked glass and Ken-Rads). I believe it improved on the Frankensteins in two dimensions: 1) bass definition & quantity, and 2) "cleanliness," the sound was super clean and I could tell there was very little distortion in the signal. Unfortunately, these improvements also came with a cost, in that I lost a degree of realness/naturalness. There was less texture or color to the sound than through the Frankensteins. I wish I could just marry the two amplifiers to get the best of both worlds, but in the end decided that bass was less important than realness, and will be sticking with the Frankensteins.  

At this point I'm starting to lean towards just keeping the Franksteins and dealing with the slightly reduced bass output. I got new cables (constructed from the 16ga Duelund WE replica wire) a couple weeks ago and that has really improved the bass situation as well. Now that they are broken in, the Franksteins do not really sound lean at all. Due to some unfortunate life situations I had been limping along with a combination of old budget MIT cables (that I'd also had to repair myself after a connector broke off) and anti-cables and it is now clear that they were actively preventing me from hearing the bass content the Franks/PRE combination was capable of.

In any case, I am growing more and more impressed with the Frankensteins. They're still in the system despite bringing in both the M-60s and the Lyngdorf TDAI-3400. I may also try the Pass XA-25, but do not really anticipate them beating out the Franks given what I've heard over the past few weeks. I may just decide to invest in getting as much as possible out of the Franks by upgrading power cables and installing Dueland capacitors.

@cal3713 thanks for the update.   I am well aware of the virtues of the Franks, which is why I am keeping them.  If I had to choose between the Franks and the M-60's, I'd probably keep the M-60's, but it would be a though choice.   Your PREs are more efficient than my SVIIs, so I can see how the balance might be tipped towards the Franks in your case. BTW, what tubes are you using in the Franks?
Its funny, I've thought about bringing in a Lyngdorf for my downstairs system, where I have significant room acoustics challenges, and returning the Franks to the upstairs system for use with smaller scale works.  But if I do that, I will not be letting go of the M-60's.
Keep us posted if you bring in the Pass.  I will be surprised if it displaces the Franks, but it would be an interesting experiment. 
I assume you are talking about installing the Duelunds in the Franks.  I haven't done that yet, but you might want to consider the PRE crossovers also.  I recently rebuilt the crossovers of my SVIIs, and the work substantially improved bass articulation among other improvements.  I don't have any actual knowledge of the PRE crossover design, but in Coincident models below the PRE, the design and parts list seems pretty consistent.  My guess is if you look you will find Solen caps and resistors, and they are not all that hard to beat. 

Just a FWIW- we've had terrible luck with the MIT and Transparent cables; we've never gotten them to play nice with our gear. No idea why, but you might want to run that comparison again if you can borrow a different set of interconnects.

Also- the amps are very transparent, but if they've been sitting a while, I wouldn't take them seriously until they have about 20-30 hours on them. Further, they need about an hour to really sound right.

@atmasphere Thanks for the information Ralph. Fortunately I was running them with my Duelund speaker cables and Ocellia interconnects. I’ll hook them up to my little desktop speakers and let them play for a couple days and then give them another shot before returning.

@brownsfan And I have the EML XLS in my Franks. I used to also have Mullards as my rectifiers, but unfortunately my tubes went bad.   I replaced them with standard NOS RCA 54Us.  Will probably give the Mullards another (3rd) shot at some point in the future. As for caps, the PREs only have one capacitor (and two induction coils) in the crossover. Isreal says its a Mundorf. I’ve seen in there and it’s wrapped so I can’t confirm whether that’s true.

@cal3713 I just recently picked up a pair of used EML XLS and also have the mullard rectifiers.  Tried the Elrogs twice, which were superb, but they failed.  Not sure if the new Elrogs are holding up in the Franks or not.  But they were to die for tubes.  As for the PREs, I'm guessing the two inductors are in series with the woofer and midrange, and the Mundorf cap is in series with the tweeter.  This is the arrangement I found in the SV IIs, except that the cap was a Solen.  The woofer had a cap and resistor in parallel, as did the midrange.  I'm guessing that like the SVIIs,  the PREs have these additional caps and resistors in parallel.  Some say replacing those parallel caps and resistors don't make a difference, but my experience was that replacing them really transformed the SVIIs.  I did not replace the inductors in my speakers.  I was told the Solens Israel uses are really good and there was no need to replace them.