Software/Hardware Hybrid: 1998 Yamaha DSP Factory DS2416 + AX16-AT 4-band eq, Hi & Low bands can be switched to Hi-pass & Low-pass Filters *Unknown slope. https://usa.yamaha.com/files/download/brochure/4/320264/ds2416.pdf http://www.oldschooldaw.com/manuals/cubase/CubaseSX/SX/PC-2002/cubaseSX_v1.… https://uk.yamaha.com/en/support/updates/index.html?c=proaudio&k=DS2416 Creamware Scope pci / Soniccore for macOS 9.2 / PowerPC G4 G5 but also worked on Windows, and OSX 10.4 Ensoniq Paris .. Software Only: 2006 - 2019 thuneau allocator for WinXP https://web.archive.org/web/20190716065853/http://www.thuneau.com/allocator… https://web.archive.org/web/20140530212406im_/http://www.thuneau.com/images… had -24dB/Oct, -42dB & -60dB/Oct Hardware: Yamaha D2040 "Digital" was interesting, F1040 "Analog" JBL DSC 260 & 280 "Digital" were rebranded BSS Omnidrive 260 & 280 JBL had Orange LCD display, BSS had Blue, maybe DACs were different JBL had 20-Bit, dbx 260 "very popular" had different DSP algorithms, included a digital version of the dbx 120xp / 120a sub-harmonic generator. dbx has many models of the 260, 360, and very large Pro models 480 / 4800... there were "rare" brands, like Dynacord, EV, etc... Analog: DOD 835 dbx 234xl JBL M553 / M552 Rane AC Ashly XR / SC Furman X-424 / X-324 / TX-3 Peavey Crown Crestb cpc 1234 Behringer Symetrix 524e were the "go to" UREI 525 was more rare, BSS FDS-318 was the most desired analog crossover from BSS. all other Analog crossovers from BSS had Fixed resistor network cards, 318 was variable. Klark Teknik DN800 was also fixed network cards, DN 8000 was "Digital" QSC had an Optional Add-On Crossover Card for PLX, DCA & PL2 amplifiers, similar was included by default in PL2A Peavey CS had "filter plug type crossovers" like vacuum tubes, but pre-made crossovers. some speaker brands have its own crossover, like Yorkville, Apogee audio, Bose. Crossovers could be done "Analog" Horn loaded loudspeakers, increasing the front chamber of the speaker before the Horn Throat. creates a natural roll off in the highs. Horns are "Band-Pass", and can be "Tuned". Most Pro Audio Class-D amplifiers have DSP built-in, to replace external digital crossover units "lower cost". Hardware outlast Software, Software is Vaporware. Hybrid depends, sometimes 60/40 other times: 40/60. for example: RME hdsp9632 pci card works flawless but... Linux source code has small bugs since Ubuntu 13 probably Cosmic Ray Flip type, bug accumulate, becoming almost unusable in 20.04 LTS with Alsa driver. Most Analog crossovers & eqs emulate Coils / transformers using Op-amps + capacitors. most have Servo-Balanced I/O's to emulate Balanced I/O Transformers. everything is an emulation of an emulation. LOL