Nothing I have is irreplaceable, but for my home system I would keep the Hagerman Cornet2 phono pre-amp since I built it and it works.
Now if I had to sell
everything then I would keep the modified JBL L88's that are in my shop, which are no longer 88's but hot rodded home made L100's with all JBL drivers, heavily braced cabinets, and re-done crossovers. There is a reason these are still cult favorites, these babies rock.

Wayne