Essential information that you should know when looking at a secondhand SSL, with a bit of SSL history thrown in. Why buy a used SSL? No-one should buy a console as an investment however a 4K/6K SSL will, if properly maintained, hold its value which cannot be said for any new console or DAW. In terms of reliability these desks have stood the test of time and with the modular design fault finding and maintenance are really straightforward, spares are easily available. The 4K, 6Ks etc. are much more efficient on power consumption hence generate much less heat than the likes of the VRs and 9Ks so the capacitor failure rate and switch oxidation is significantly better. Your studio will have probably the most "industry standard" console in the world; this makes great sense particularly in a commercial environment. Since the 1980's more music has probably been recorded on SSLs than any other high end console. (Remember that cheesy Billboard quote?) When you buy an SSL you don't just get a desk you get EQ and dynamics on every channel and the famous mix amp and compressor all of which adds up to the mojo "SSL sound" thing or whatever you want to call it.