The DAC on the Clip+ is only 16 bit, so there is no advantage to using 24 bit. Rockbox will decode any FLAC file, but they’ll be converted to 44.1k/16 for playback. The sandisk firmware doesn’t decode 24 bit flac at all. BTW, you probably already know this, but LPs are less then 16 bit, so there is no loss of quality from converting to 16 bit.
LPs are analog. that’s 1000x better than digital at any sample rate and bit depth for some.
This is a common misconception. The dynamic range of an analog system determines the number of bits required. Thus, as the dynamic range of LPs is quite low, they need relatively few bits when quantized. Depending on your equipment and the age of the LPs (dynamic range decreases with each playback due to damage from the head), you need something like 10-14 bits. 24 bit is nice since it means you don’t have to be as careful about preamp when recording, but it doesn’t actually improve quality anymore then converting an MP3 to FLAC improves quality.
I can hear the difference between mp3 and lossless digital formats and distinguish between different sample frequencies.
There is no meaningful difference between 48k and higher sampling rates, so if they sound different, you likely have a problem with your equipment that is degrading audio quality. You may want to get a sin sweep tone and check for aliasing.
It cost a fraction of what I have in my studio and living room 