Replaced this morning the original 43year old fuses on my Infinity Quantum Jrs ...nothing else in my cd set up has changed and everything seems tighter and slightly more separated in a good way, guitar strings have a distinctive twang each string almost ..(bad description twang but not sure how else to say it) Now before we all go "fuse war" .... these are brand new fuses but NOT audiophile...simply obtained from an electrical supplier in the UK as getting a 32mm x 6.3mm 2.5v fuse wasn't straight forward here (i'm replacing a USA made fuse of course with the Infinitys from 1978 being US built) The fuses i got are Schurter costing £1.21 ($1.67) including the tax per fuse ...these are the expensive ones !!!!!! as they come with all the safety compliance paperwork RoHS, UL & CSA but what the heck ...and i only had to buy a pack of 10...next day delivery a very reasonable futher £6 https://uk.rs-online.com/web/p/cartridge-fuses/1678604/ I had last year cleaned the fuse holders and the ends of the old fuses with deoxit...so i wasn't expecting any changes to the sound from putting in these very ordinary fuses It was simply a quick fix as in swapping between stax headphones and wanting to listen to the speakers i had inadvertantly left my BenchMark Dac1 HDR set to the "Fixed" level of out ....Ouch i know smacked wrist ...a moment after switching the first Mono X amp on ...VERY LOUD music played and as i moved to turn the switch to variable output silence from that speaker ... upon checking the amps and both speakers thankfully all the damage done seemingly was to the fuse in the left speaker ...nicely blown ... hence the quick fix So my question to those many on here who understand such things am i hearing real differences or is it because i couldn't listen to the speakers for 24hrs ? ... do fuses deteriorate over many decades ? could it be now i'm simply hearing what these vintage speakers are capable of ? and before they were veiled in some way ?