Let's clear things up a bit...
The number of bits in a DAW's architecture limits the amount of addressable data in RAM... At 32 bits, there are 2^32 addresses, which is just over 4 GB; at 64 bits, there are 2^64, so we no longer have problems.
RAM, when associated with a 64-bit DAW, limits the number of loadable VSTs. For example, if I had to load an entire orchestral ensemble, perhaps with 8 GB I would be tight on space, so it's better to opt for 16 GB considering that an entire string section, if of good quality, sucks up at least 4 GB; then we add the piano, winds, percussion, etc., and we easily approach the saturation of 8 GB. If you get close to saturation, the system becomes unstable because if the DAW or other processes need to load more data into RAM, the PC slows down.
The hard disk speed implies the ability to play back what we have written in MIDI without having to use Freeze functions (in Logic) or consolidate functions (in Pro Tools). Basically, if I make everything play in MIDI, the players must continuously refer to the RAM to play the samples of the corresponding MIDI notes at the expense of the hard disk; therefore, if the hard disk is too slow, one or more MIDI tracks are rendered—keeping the MIDI track but muting it—so that the workload for the hard disk is lower, as it no longer has to play MIDI data to be addressed to the VSTs, but rather a rendered wave track... Keeping the MIDI track on mute ensures we can still make changes, i.e., being able to go back by deleting the audio wave track and re-recording it once the changes are made, then putting the MIDI track back on mute.
If a solid-state hard drive (SSD) is used, the data transfer speed is much higher than any other standard magnetic disk hard drive; therefore, it is possible to almost always keep everything in MIDI without having to consolidate tracks.
Regarding voices...
32, 64, 128, 256, 512, etc., are the number of samples that can be played back together. The sound quality is not affected, so you don't hear better or worse by varying the number of voices; rather, polyphony is affected. A piano has 88 keys, so 128 would be fine, but we must consider that in some cases we use tonal pedal + "una corda" (una corda) pedal; therefore, to be sure that all voices are playable, we should work with 256 voices. But then why in a player like Play do we go up to 1024? Simply because it is possible to mix different positions (3 perspectives, to be exact), so the number of voices to guarantee polyphony goes up to 1024. The same argument could be made for other players where we insert various libraries; for example, in Kontakt, we can insert many libraries by assigning a different MIDI channel to each. In this case, we must guarantee polyphony. What happens if the number of voices that should be played is less than the polyphony number set on the player?
Voices are loaded into an array of addresses that performs the routing of a MIDI datum to a position in physical RAM, which in turn redirects the data to the corresponding sample. If the number of data items in the queue exceeds the available positions in the array (the number of positions of which depends on the set number of voices), the first voice called is deleted to make room for the last one dictated by the last incoming MIDI datum. Practically, at an acoustic level, the first sound played relative to the time axis is cut off to allow the last one to be heard.