Is the B2030A silent? I mean the amplifiers of course. Any audible hiss and/or hum at all?
As for the 2kHz peak you claim exists. No such peak exists on the passive version. One of the biggest gripes I do have with the passive version, as opposed to the active version, is that they obviously used a very stiff surround on the passive one to raise the speaker's Fs substantially, thus resulting in a high F3 for the speaker. The active version apparently uses a soft surround, allowing a far lower Fs, and far lower effective cabinet tuning. Perhaps something that was done to act as an incentive to purchase the active version over the passive one?
what source are you using and what kind of connection ?
Also, they are autonomous. There is no "left" or "right" speaker. Each has its own power and signal input. Its basically two identical speakers. With the right cabling and signal-sources, you could run any number of speaker channels by simply buying more speakers.
Right now, i'm still waiting for an external soundcard to appear on the market which fits my needs. Until that happens, i'm on an onboard laptop soundcard, which coincidentally does not have the typical flaws associated with laptop soundcards (no audible hiss, no strong signal degration). Since that means that i do not have balanced signal sources available, i didn't bother with doing an XLR connection and just used a properly shielded 2 metres Y-Cable from 3,5mm TRS stereo to 2x 6,3mm TRS mono.
The problem here is not the balanced output (in my point of view), a bigger problem is that you are using the phone output, aren't you? Phone output its an amplified output, so you are amplifiying 2 times the same signal, first one with a very poor amp :( and sending this "degradated" signal to your active speakers.