I don't know what your speakers or room sound like, or how your musical tastes run, and I can't tell you anything about the Belles. My experience owning a DNA-125 has been very positive, though it's primarily been a back-up amp for me (driving Thiel 2.2 speakers in a mid-sized room, playing mostly rock and jazz). Not a 'giant-killer', if there is such a thing, the 125 won't fool you into thinking you've spent three times what it cost, but neither will it make you wish you had. (After you read what follows and before you conclude that I'm damning it with faint praise, please keep in mind that I'm just describing it more honestly than you'll almost ever see in a magazine review, that I do *like* this amp and that no amps are perfect.)
Pluses are that it's well-made, cool-running, not anemic with the power (as some moderately-priced solid-state amps in the 100w range can be) -- this is a notably composed amp at volume -- and that its sonic shortcomings are mostly subtractive and musically consonant, indicating I think quality engineering for a product in this catagory. Unlike the DNA-500 I also own (and probably the 225 from the reviews I've read), the 125 actually tilts slightly toward the dark and full rather than the bright or lean in terms of tonal balance.
Strengths include: a deep soundstage and solid, stable rendering of images with good dimensionality; a clean and edge-free way with transients; good bass power and control, not overblown or disconnected from the rest of the spectrum; and perhaps most importantly, an almost entirely benign harmonic structure (again unlike some others in the catagory) and an essentially coherent overall presentation.
Areas not as strong (none egregious flaws) include: somewhat limited ultimate extension, in the bottom-octave bass but more noticeably in the treble top-octave (at least with my speakers, which don't plumb the bottom octave either), where it tends to 'burnish' cymbals a bit; microdynamic articulation not as fast or deep as with better amps, leading to a slight 'liquid' effect that can subtly obscure precise expression on demanding passages; soundstage height and airiness as well as image size and separation are a little curtailed compared to the best; macrodynamic punch and scale are naturally somewhat compressed compared with more powerful amps; resolution of very fine detail not as explicit as with better amps; not completely free from a slight 'mechanicalness' and 'boxiness' common to SS amps not priced in the premium range; very minor 'electronic' or 'wirey' textural deviation just noticeable on acoustic instruments; equally minor 'rubbery' deficit in bass definition; and a slight 'thickening' in the mids -- at least compared to my other amps -- combined with an equally slighty rolled treble beginning in the presence range, that for the most part doesn't really rise to the level of an overtly noticable coloration when listening and is often pleasant if not downright welcome with a lot of material, but can take on a slightly 'hooded' cast with other material.
But more importantly than its relatively minor lacks in terms of ultimate transparency and neutrality, the 125 is basically free from the kinds of glare, grunge, coldness, hardness, glassiness, boominess, thinness, opaqueness, forwardness, vagueness, flatness, tiziness, enharmonic signature, or other sins that can make listening to a 'budget' amp seem like too much of a compromise. The compromises in this amp seem well-chosen, being an essentially smooth and relaxed performer, and I think a sufficiently reliable window on the music for the money to recommend easily if you think this might complement your speakers and the rest of your system.
Oddly enough, given my description of its sound, in my system the 125 seems to respond best to power cords that emphasize smoothness and noise reduction (not that it's noisy) over speed, attack, and extension, gaining a bit of authority and increased textural naturalness. And don't forget that, as mentioned above, Steve McCormack's SMc Audio mod upgrade path by all reports can probably improve or transform all the characteristics I've noted, and my time with his amps has made me seriously consider going that route myself as an alternative to my 3X more expensive and 2X as powerful tube monoblocks, which themselves do not beat the stock 125 in every area. (In fact, you can hear hints of some of these improvements simply by running the stock 125 with one speaker disconnected, as a monoblock, but I haven't tried bridging mine.)
