I use the Linn 12.45 sub. This sub is without issue with the new power supply (new internal amplifier module). The older (non-upgraded) had a VERY noisy fan that use to come on randomly. The Akurate sub is nice too. It is a bit tighter but one might argue "less sub" if that's a term! Also, I recall hearing issues about the driver hitting the front grill on the Akurate when palying VERY loud. The 12.45 is a large piece! It does use up some realestate! A new 12.45 from Linn should have the Chakra amplifier in it. I have not heard the rel.
cheers