Thanks for the well thought-out response. I did some websurfing too, and found that treble attenuation in air is actually very small, something like -0.3dB per additional meter of distance at 15kHz, while the monitors themselves are rated to accuracy of about +/-2dB across their frequency range. So in a typical home use scenario of maybe 3-4m the attenuation shouldn't be a big deal and I certainly don't see it making a difference in favor of "HT" designed speakers. The chart you linked doesn't contradict this view. It doesn't indicate longer distances are a total no-no, it just warns that longer distance potentially allows room characteristics to alter the sound. What the chart makes me wonder is, why would the room not affect the larger speakers as much?I'm honestly not 100% sure. I would think that it has to do with dispersion, off-axis response, the way that frequency response varies with distance (directionality of higher frequencies vs. omnidirectionality of lower frequencies), and intended listening volume. Here is a chart from Genelec:
http://www.genelec.com/documents/other/step_by_step.pdf
Genelec naturally has reasons besides absolute sound accuracy to push the larger speakers. You need more powerful speakers to put out the same reference sound level farther out; larger speakers with a wider freq range manage better without a sub; and I bet they wouldn't mind selling you a more expensive speaker, either 😉
My own system is actually the 6010a monitors and the 5040a sub in 2.1.
I don't think that comparison tells much about the sweet spot of the KRK. In any case, the RP G2 series has a +1dB HF adjustment which, according to the data I dug out above, should fully compensate for HF attenuation ~1m farther from where the optimal position without adjustment is.The 8030A is a studio monitor with a 5" bass driver, a 3/4" tweeter and 40W each to bass and treble (and retail for $700 per speaker). So in terms of drivers and amp power, they are comparable to the KRK Rokit 5's. According to Genelec's chart, the sweet spot for listening to these begins at 0.5 meters, peaks at 1.3 meters, and ends at about 2 meters.
OT: Genelec chart doesn't really specify a sweet spot peak, at least their labeling simply calls it a 'typical' distance in a studio. Could be just because a single recommendation is easier for some people to wrap their head around than a range.