[tigeba]

As a practical matter, the CPU has to deal with IO as well, I don't believe any 486 systems could handle this.

DSP based systems struggled a lot with IO in the late 90s until faster SATA drives became ubiquitous. Lots of them used SCSI or exotic hardware cards to deal with large track counts.

[PaulDavisThe1st]

The first version of Ardour was written on a 25Mhz 486 and could record 24 tracks of 24bit 48kHz audio without breaking a sweat.

It did have a SCSI drive, but in 1999 I did not consider that "exotic", having been using them on various Unix workstations for more than a decade before that.