Expensive tweaks-are they worth it?

I found that the Argent Room Lenses were one of the most cost-effective and significant tweaks I have ever used. Bass performance in my room was much improved with deeper extension as well as taming a mid-bass hump. In addition, soundstaging was dramatically improved with much better delineation of individual instruments and vocalists.

I agree with Albertporter, the Walker HDLs were a definite improvement to my Maggies. I use 2 sets because they are biwired. I purchased them after hearing them on a pair of Sound Lab Ultimates. He correctly points out that your system must be 'mostly correct' to appreciate them.

The Walker HDL's do make a difference. Whether that difference is a good thing or a bad thing is purely subjective. Thing is, $300 will buy you a fat stack of records. Something to think about...

The Walkers do make a difference on my dynamic system as well, although I think they're expensive for what they are (not the improvements). The designer of my speakers did a measurement at the tweeter with the HDLs in and out of the system and there actually was a measurable smoothing of the treble output. The room lenses didn't work for me, but my system is almost an omnidirectional one, that probably has a lot to do with it; on a more conventional speaker system my result may well have been different.

I too gained a significant improvement upon using the Walker Audio HDLs on my Thiel speakers. They are very much worth the price I paid for them.
I have it about 6 months on my speakers and I forgot that it's in there. I tried to take it off one time when I was re-positioning my speakers,the result was unbearable,I did not even finish listening to one track and I have to put it back in.
It's like a lot of good things that we have and take for granted, we will never know how vital it is until we loose it.