Expensive tweaks-are they worth it?

I cannot speak for the Argent Room Lens, but the Walker HDI is a very worthwhile high level tweak. It should probably be added after everything else in the system is mostly correct to fully appreciate it's value.

To put price in perspective, the HDI at retail is about the same investment as a foot (or less) of the interconnect cables usually found in a high end system.

The performance is distinctly audible with my Soundlab speakers, adding impact and dynamics to the bass frequencies and smoothing the extreme high frequencies while improving depth of image. I have had others tell me that similar performance gains were had with dynamic speakers as well.

ditto to Albertporter's comments and observations on the Walker HDI.

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.