It’s really fine, with some education and adjustment of your expected resale values. If you buy something at full retail, you’re gonna take a bath on its resale, even if it’s the very next day. Some brands hold up in value better than others (yes, McIntosh being one of the gold standards there). New hot items can command a premium, but that rarely lasts. When you look at sold used items over time, most are going below 50% MSRP. After the initial big hit though, depreciation tends to level off. So you’d either better get a hell of a discount when buying new, or buy used to start with.
If you get a used item that sounds notably worse than a new one, 9 times out of 10 that says some very BAD things about the manufacturer (inconsistency, bad reliability), rather than the fact that it’s used. Audible problems tend to be very obvious, and sellers with good feedback are not trying to pawn off broken gear.