I would go with the preamp. It's the next piece from your source before passing the signal to your amp. You always want to retain as much as possible of the original signal had work well for me. Good luck.
Power first then pre. If you look at the two sections of your integrated as separate components, the pre section (which is almost as good as a decent separate pre) when combined with a really good stand-alone amp will come pretty close sonically to a complete 'separates' system.
Whereas a new separate pre driving the amp section of the integrated won't really get to shine, and the result won't sound much better (if at all) than the integrated does now IMO.
And besides, if you can possibly try a few amps using the pre in the integrated, you'll likely be able to make a good amp choice. On the other hand, were you to try a number of different preamps driving the integrated's amp, the pros and cons might not be very obvious that way. Better to wait and audition preamps after you've made your amp selection. That would be my advice.
I had the same dilema a few years ago. A owned a well respected integrated. I was trying to upgrade one piece at a time and was auditioning a few amplifies. Quite by accident, I rotated a preamp into the chain and was shocked at the upgrade in sound. Secondly, my experience has demonstrated that a preamp is a more significant and impactful upgrade than an amp. I would experiment with upgrading to a stand-alone preamp first.
PS: I speak from my experiences with different equipment than yours so factor this into my comments.
You realize of course that your MF A3.2 only has a PREAMP OUT and not a PREAMP IN, so you will not be able to use your MF A3.2 as a power amp with a new preamp.
I learned this the hard way when I purchased a MF CD PRE24 (preamp/cd player combo) to use with my MF A3 integrated amp and wound up only being able to use the cd player portion of the MF CD PRE 24. This led to a purchase of a MF A300 power amp and a sale of a MF A3.2 integrated, when all I originally wanted was a matching A3 cd player, which by then had been discontinued. I had received a great price on the CD PRE 24 (it is in use today with a Prima Luna Prologue Five power amp) and I liked all its preamp capabilities, but I could not use it with the MF A3 integrated.
Why did MF do it this way with A3/A3.2? Because they saw owners using the A3/3.2 with other power amps (like mono blocks)or a HT receiver, not another preamp.
So, about all you can do is change the power amp at this point ... or get another integrated (think Prima Luna Prologue One or Two for tubes).
Thanks for all the great responses so far. I am leaning toward acquiring the pre-amp first.
Rar1 - The MF A3.2 *does* have a pre-amp in, in the form of the Auxiliary 2 (Home Theatre Direct) inputs. To quote from the manual "When selected they are routed inside the A3.2 directly to the power amplifier circuit, which is not controlled by the volume adjustment." As far as I can tell from manuals on MF's web site, early versions of the A3.2 did not have this feature.
Well lucky me. Spoke to Dan Wright and called the YBA techie department. The Yba does have a video input, which can be used as a preamp in, because there is a facility on the hand control to defeat the internal preamp. This was created for video processors and the like. It may be a match made in heaven. Dan said that he will be adjust the gain on his pre to match up just right with the Passion. This is cool. Grant, do you think it would be better to wait on the Wright Preamp until I have Alex's baby (APLDenon 3910)since his has a pre,which may obviate the need for the Wright pre. It seems that many who have the APL, prefer, however, to use their own preamp. What do you think?
This is the which came first thing: the chicken or the egg? Which should come first: the amp or the preamp? I think that the best thing for me to do is groove with my Passion and Definitions, until the wife says "okay honey, I want you to order that fabulous cdp you have been waiting for all winter. Oh, and hon, that's 1.5 carets per ear, not total weight." The synergy may be just right. If not, I'll take it from there, but I cannot imagine the sound being anything but wonderful. What I want? I'll have to wait and see.
Sorry I never answered your question and filled your thread with my agenda. Go with the Preamp, absolutely, before the power amp. It (forgetting power, and assumming that is not your problem) will yield dramatic sonic benefits to your rig, particularly if you go with the Modwright. If I were to own separates that would be the pre I would go with. Dan is a great guy: Listening wise, I have no experience with his preamp, but I know enough audiophools who own one, that are very happy campers.
I finally sold my Passion and am waiting on an Audion Sterling MKI with British vintage Gold Lion tubes. Should be a match made in heaven with my new speakers. Hopefully.