@coxhaus - I agree, not so much by preference, but moreover that, as you said, PoE+ is all but included on basically most stuff being made now. I'm sure the OP wouldn't mind PoE+ and/or higher wattage, as long as it's the quietest option possible with 24+ ports.
@MustacheSwe - As you probably know, most 24 and 48-port models will have active fans, typically at 35-40 dB or higher volume. That being said, there are exceptions, but the list is short. Here they are:
- Ruckus (Brocade) ICX 7150-24p / -48P
L3 Basic | CLI with web interface | 370W PoE/PoE+ | "Fanless mode" when pushing <150W PoE | -24P is $1200 new, $800 refurb (eBay)
- Cisco Catalyst WS-C2960L-24PS-LL
L2+ | CLI with web interface | 195W PoE/PoE+ | Fanless/Silent | $1100 new, $700 refurb (eBay)
- Zyxel GS1920-24HPv2 / -48HPv2
L2+ | "Smart" Web-Managed | 375W PoE/PoE+ | Quiet fans at 27.2 dB (-24HPv2) and 26.5 dB (-48HPv2) | $380 and $440 (Amazon)
Nothing silent enough at 24+ ports: Cisco SG series, HPE/Aruba, Extreme, Allied Telesis, Netgear, D-Link, TP-Link, Buffalo, FS, Ubiquiti, Mikrotik.
I also excluded triple-stacking silent 8-port models, such as HPE 2930F's, due to awkwardness and cost.
So that's basically what's out there. If you can live with a little bit of whisper-quiet noise, the Zyxel's are probably your best bang for the buck, and simplest to operate.