I have got the BSS London BLU-16 of off the ebay for $260 and tax, and the extra output card for arroud a hundred. Not diy but not that much more than minidsphd plus the rack drawer, balanced to unbalanced converters and the converters other way if to buy all that stuf. Also blu has less limitations on fir taps usage. Bss audio architect does accept .csv export from popular software packages. I don't have four ways system, so I did set Vrx932la plus a sub for a test as a three way. Got pretty decent impulse response. Phase is within 40 deg down to 100 Hz and within +/- 7 deg from 300 to 20k, not too terrible for the first try. Crossovers are 96 lr at 1k and acoustic lr 24 at 85 Hz for sub, with some iir flattening before fir filters.
Just to see the DSP usage i added another pair of ways to make it into four ways.
The blu16 now is set with three inputs and eight outputs. Each of the mains consist of input gain, delay and system eq set all as stereo pair, the super high channel with another parametric eq , delay, fir filter, limiter, gain. Highs are similar, but uses bss crossover set as high pass lr 24 at 800 hz to clean up the low end of the fir. The crossover also includes delay and gain controls. The lows uses parametric eq down low, linear phase lr96 fir on top and the stereo crossover at 85 hz. Driver time allignment is implemented as a delay inside the crossover block.
Input 3 is for aux fed subs and feeds two of the otputs with delay between them to set the radiation pattern. It also features shared gain control with mains, parametric eq, and the crossover with subsonic filter and limiters.
The limiters are of two stage variety, suposedly peak and rms but bss is little unclear on to which of the stages the controls belong to.
My Fir filters have 820 taps at 1 khz crossover and 320 taps at 3 khz (not in use with vrx), to keep overal delay under 10 ms. Maximum of 6700 fir taps can be specified , I don't know if per filter or total.
All of this did put DSP utilisation to 80% or so.
Access to the unit is over the wired ethernet, but wifi via router works just fine.
Hope this helps some...
