I cannot speak of the 325i+RA1 combo, but I can comment excessively on the 325i (new, silver edition w/ bowls) with the Little Dot MKIII with Mullard M8100 tubes...
... but to keep this short: it's a
wicked combination.
The bass is just perfect with this combination, offering me everything I've wanted in a headphone setup for a long time: punchy bass with plenty of extension into those lower frequencies, excellent mids (and Grado is known for their midrange-coloration, which I happen to love), and the elusive high frequency response & perceived speed to go with it. The bass and lower midrange are helped heaps by the LD MKIII + Mullards, no doubt about it. I've not even bothered to try some of my other tubes since plugging in the 325i's--it's just too good sounding as it is. Call it spikey, peaky, colored; I call it a damn good setup for the money.
This setup performs exquisitely with 1960's hardbop jazz (ex:BN), small-club jazz trios (ex:Bill Evans), 1950's/60's lounge (ex:Les Baxter), classic rock (ex:VH/LZ), pop (ex:U2/Garbage), indie (ex:Interpol/Pelican), prog-rock (ex
reamTheater), house (ex:Laurent Garnier), drum&bass (ex:LTJ Bukem/Marcus Intallex), tech-* (ex:Ben Sims/John Tejada), classical piano (ex
ebussy->Rubinstein).
On a side note, the 325i's improve a great deal from decent tube amplification. I recommend tubes with this beast, having demoed them on two separate SS setups prior to purchase.
Another thing to note that you should know about the LD MKIII is that every headphone I've plugged into it has sounded
great. The Beyerdynamic DT880 2005 250ohm, Sennheiser HD580 (w/ 600 grills + hd650 cable), and Grado SR60's all sound fantastic and noticeably better plugged into it. Of all the headphones I own, the 325i's are currently my favorite, eking out the DT880 which was my preferred headphone in this setup prior. Anyways, the fact that the LD MKIII does so well with such a variety of headphones from different price ranges with
widely varying impedances says quite a lot about the quality and versatility of the LD MKIII.
Hopefully more can comment with RA1 experience and maybe even LD MKIII & RA1 comparisons, but I think that might be a bit difficult to unearth.