i'm kinda late to this party… but i just discovered the thread today, so i have at least a lame excuse.
for starters: i've been using PureMusic and PureVinyl for 10+ years. and ten years ago i bought a Metric Halo Lio-8 which i later upgraded with 8 channels of mic preamps. i bought the MH for two reasons that are important to me: #1 the volume control is done in the analog domain after the DAC section i.e. no bit truncation. #2 MH had already back then the reputation of being upgradable. this proved to be true when 2 or 3 years ago, MH introduced their 3d upgrade (basically a much improved DSP section plus the introduction of MH Link and Edge Cards e.g. for S/PDIF or additional AES inputs. MH just recently introduced their Mk IV versions which improve on the analog section with newer A/D and D/A converters, less power consumption and relays as output mute instead of solid state switches.
my speakers are 3 way horns, my amps are all DIY (tons of tube and SS; for years i have been using a "spud" (a.k.a. one-stage tube amp, in my case input transformer > 6S45π triode > output transformer > TAD TD-4001. 0.8 watts output are plenty loud with 115 dB/W/m compression drivers.
i am absolutely happy with this set-up. the crossover in pM/pV is really superb and gives great freedom in creating filters that are far superior than the textbook 2nd, 3rd or 4th order BW or LR filters with common crossover frequencies. one advantage of digital crossovers (well executed ones, at least) is increasing or decreasing overlap. normally the overlap is set that the LPF/HPF slopes meet at -3 dB or -6 dB. depending on the filter this gives flat frequency *or* flat phase. but by spreading the slopes farther apart (e.g. -8 or -12 dB) or doing the opposite, narrowing to 0 or even +2 dB, is a powerful tool to improve the sound at the crossover frequency. contrary to the OP, i think LR filters suck. big time. i'm not particularly fond of LR filters. 48 or 6 db/octave slopes may be good for PAs where you want to protect your tweeters from getting fried. and they may be good for movie theaters where the auditorium slopes upwars. but for hifi? nah. i get better coherence and vertical diffusion w/o lobing and phase issues with 3rd order BW and wider spacing. the late jean-micheal le cleac'h has researched this issue most thoroughly. if you google his name and add "spreadsheet" to your search, you may find one of his spread sheets that allow you to find optimum values for 1st to 8th order filters with four or five characteristics, variable overlap, polarity, and delay. the results are also presented graphically – you can see how phase and amplitude will react, and how a square wave will be reproduced. hint: LR is not very good at this. and it can also not be tricked into being good.
pM/pV allows to assign plugins to each bus and globally. i've used FabFilter Q3 to flatten the measured response of each driver separately and at least one octave below and above the crossover frequency. as i have a Stax headphone, i assigned the four buses in the order LPF - BPF - HPF - Fullrange, with FR being at the bottom of the list and assigned to the LIO's output channels 7 and 8. i've tried to talk Bob Robinson into making it possible to run the midrange driver open end and add the super tweeter with a HPF. this would have allowed me to run the TD-4001 all the wwy to 20khz (which it is capable of) and use the Fostex 925 firing backwards to the wall beind the speaker. i have done this passively with good results (it compensats for the increasingly beamy midrange driver/horn by adding diffusing the top octave, i.e. the super tweeter just adds "air". but this is not feasible with Bob's filter architecture.
the only thing i don't like about pM/pV is the simple fact that they are 32 bit apps. macOS 14 (mojave) is the last version of macOS that still supports 32 bit apps. Bob has been so successful with his Seta phono stages that he can hardly allocate enough time to re-write the code. but as he has announced on Channel D's website earlier this year, he is working on the code and he WILL release his apps for 64 bit. so far, i had no problems staying on macOS 14.6, but a/ apple no longer supports mojave and b/ the 2022 version of Adobe's creative suite requires at least catalina. since i need Photoshop, Illustrator, Indesign, Lightroom, Audition and Premiere for my work, i pay for the latest versions, but can't use them. which sucks if you work with other people that send you files you can't open. (a dual boot set up is also no solutiion because with 10.15 / catalina apple went from iTunes to Music. the first time you open Music on a mac, it will re-write the entire iTunes database, which afterwards can't be opened with iTunes any longer. and since my iTunes library and all the sound files resides on a NAS, i can't update the workstation to 10.15 and keep the music mac mini on 10.14…
