Ditto Shoemaker's remark: what is a 1.5 Version? Also, are you going to single, bi or tri-wire? The horns are so efficient and do not necessarily create "slap-back" upstream, you should first try single wiring with jumpers (better than the ones that come with the UNOs). Nirvana is excellent. I recently designed a recording studio with DUOs and is currenlty tri-wired as follows: KIMBER SELECT (Silver) on the large horn, NORDOST-SPM REF on the small horn, KIMBER SELECT (Copper) on the Sub. SYNERGISTIC Designer's Ref works well on the Sub. Although the PASS is a great Amp, you may want to try bi-amping with a a Tube Amp up-top (finesse)and a solid state Amp (slam)just for the Sub. Also, you should use high grade Power Cords on the Subs. I have had great experience with PS-AUDIO Lab Cables for the price. I am a dealer for Pro-Audio and custom install applications, let me know if I can help you out with any of the foregoing. Morever, please let me know what you have found that works. Avantgarde is awesome and will be a design option for my clients. Happy Holidays!
