Drubin, sorry for late reply but here is what I think are the biggest differences between the Harbeth M30.1 and P3ESR. First, of course the bigger 30.1 model goes deeper and the sound is fuller and gives a more atmospheric sound in the room. I like that, of course. The bass on the small P3's, while not as deep, is on the other hand more clear, you can hear and follow bass lines easier, it's almost like they are lifted in the sound mix, which gives the impression that music is very rythmic, and actually quite rocking!
The mids are different between the speakers aswell. While the bass seems a bit lifted on the P3's, the mids seems a bit lifted on the 30.1's, which gives vocals a lot of presence in the room, and there is no bass that "covers" the vocals, that might be the case just little bit with the P3's.
The highs on both speakers are very smooth, not overly bright or sharp or anything like that. That means some details might get lost compared to some other speakers, but personally I much prefer smooth highs instead of anything else, on the long run. That is why I got Harbeth's in the first place.
The P3's are easier to drive, I have used three different amps and they sound great with every one of them. The 30.1's are more demanding, but I haven't tried the speakers with a modern big power amp, I might do that later, maybe I will gain some more bass control, that I already have with the P3's. Both speakers are very easy to integrate in the room, there's no booming bass and I can place them pretty much anywhere, compared to many other speakers that requires a lot of space behind them. The P3's are great all round speakers, works great with every music genre and movies aswell, and they are great near field monitors, if you want to put them on a desk, that would work fine. But I like them best put on speaker stands or on a shelf. The 30.1's are very soft, warm and nice in the sound, I like them a lot aswell. If you have a small room, the P3's are perfect, the 30.1's are good in any room.
