I probably should have started a new string concerning specs, but since it was asked. There is an old saying that if the specs measure good, the sound can be good or poor, but if the specs are poor, the sound suffers or is never optimum. One can kinda get away with some specs, but FR is pretty important. Even 1% distortion (-40db) seems high.
Based on decades of experience and testing, there are sonic problems especially associated with FR deviations. Since the signal is down approx -3db, an accurate output would also be down that amount. So if the bass seems sufficient, the actual design itself is not the problem, but the parts, solder etc selection.
"Boosting" the sound in the bass region with parts etc, to fill out the sound, is not an accurate boost since the parts have different characteristics than an actual string/electric bass, cello etc and has different characteristics.
For example, the winding construction, DA, DF, termination, etc affects the sound of a capacitor, with some capacitors artificially excentuating the bass. This can easily be demonstrated by using an electrolytic or even mylar capacitor in the circuit design.
However, the distortion/bloating of the bass is not limited to just the bass region. It also occurs throughout the bandwidth that the inferior capacitor has to handle. So the upper bass, lower mids, mids etc are also affected, and distorted.
A little story. I have heard old amps/preamps using electrolytics that sound relatively thin because of the use of small coupling caps to minipulate the mids, but then the bass suddenly whops one over the head because it is so fat/bloated/distorted. All because of the electrolytic cap(s) in the circuit.
Anyway, one can tell at a moments internal peek, either of specs or peeking inside, if there are design/parts problems or not.
Hope this helps.
