If you can wait until the release of the Heritage Horn loaded subs later in the year, they are tuned specifically for La Scala (and the rest).    They are also as, or more sensitive than the LD so you don’t compromise on distortion. Something that’s readily apparent after just a minute or two of listening.    I will post a link to a tread where that is discussed more. 

If you haven’t used the room simulation function in REW I would urge you to do so in order to investigate subwoofer placement anf the optimism number of subs for your room. I have paired my La Scalas with two minimally-sized THTLP subwoofers. The performance is very good. Four subs would be optimal for me but that isn’t going to happen for reasons of cost and WAF. A THT or THTLP build is about USD$1200 which is in the same ballpark as a low-end REL or SVS sub.

that resistor/“capacitor” is an aftermarket addition of a Klip circuit

https://nh.craigslist.org/ele/d/pelham-klipsch-15-belles-cabinet-horn/7829282002.html     Alight, it's jumped the shark

Trey Hensley - born in Johnson City, tn.    

NITAAAAAaaaaaaaaaaaaaa  🤪       👍

Hi Dave. I just posted this very same topic on another forum yesterday:   Greetings. Wanted to get some members' opinions regarding subwoofers. I have no personal experience but have read differing opinions regarding this matter, so you'll have to excuse my ignorance or lack of experience. My current setup consists of LP12 TT with Lyra mc cart, Esoteric SA-50 CDP, and Innuos ZENith server, but no streaming source. I have an EAR Yoshino 868 preamp, 300B & 830B SE and EL84 PP amps powering Klipsch La Scala AL5s. My system is set up in an area that's 12 wide by 9 deep that opens up into an 18" sunken 15x15 living room and wider dining area, all having hardwood flooring. I am very happy with my system but sometimes wonder if I would benefit from REL subs. I've read differing opinions. My trusted tech/amp builder says I might be better off going with passive EQ or room treatment. But room treatment is not an option with my very supportive and understanding wife. I would appreciate educated personal opinions regardless which side of the isle you're in. With gratitude in advance.   I have thought about this matter but wonder about cost/benefit or risk/reward equation.  Wishing you luck and hope you find some sound advice.

Regular plywood , chipboard , Birch , Aspenite OSB , MDF  will work ,   Fir plywood would be my 1st choice 

Hi, An Australian guitar goddess who gives her guitar (just a PRS signature, crazy personal edition) to a Mexican woman, our friend  @Full Range  will like that 👍       😍

@Cinema600hopeful, Welcome to the Klipsch Community forums.   Cinema 600 - How to Check Firmware Versions   BAR 48 firmware will not work in a Cinema 600 and shouldn't even install. To verify that you have installed the correct firmware, see the link I provided.   It would be helpful if you could provide additional information about what does and doesn't work. Is it only the sound? Does the soundbar show the correct firmware? Does the Klipsch Connect app work. etc The more information you can provide, the easier it will be for someone to help you figure out what is wrong.