Timpani, what a difference a day makes in the life of an audiophile. After weighing up the benefits $4000.00(AU) was going to make to my system invested in either a line filter or in a high end re-design/re-wire & external x-over mod to my Rens, I realized ok, they're in great shape BUT they are 14 years old, and wiring and caps would have degraded to a certain extent...added to which, that's an opportunity to replace $8 per meter internal cable with $800.00 per internal wire & replace the 5% standard value caps with the best sounding sounding caps around. All the comments from IRS-Sigma owners I admit at first made no sense to me, but with your clarification, yeah obviously their superior crossover does make a noticeable difference. The re-design I am planning however is on a much higher order & results should be stunning. The new x-over will make the Rens more efficient as well. This is significant in itself in with this mod, I should be able to achieve the same stunning results as guys like Clavil running a single big iron amp & pre. I think that is a smarter solution to bi-amping, do you agree? And yes, I will proudly wear my gold medal for the backflip, thank you!