Monster Regret!!

No matter what it is your testing or considering for your audio system , always hear before commiting and let your ears and TASTE make the final decision .

Take your time . Listen while you are relax and in a good mood . Sometimes that which might be considered a small and subtle difference on long term listening might actually be ( because of our ears incredible hearing acuity ) very audible . 

But the bottom line is to take your desicion based on your ears and taste 
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On the subject of equipment design to protect your investment there are many on the market that will do it . As long as it doesn't have detrimental effect on the sound your'll be ok . Many even makes your system sound better . I've never personally tried a Monster Cable line conditioner or protector but have talk to some buddies who have which I trust and all say they work and don't have a negative impact on the sound . 

So as long as they protect and that is what your looking for Monster is ok . To finish I would like to recommend what I use which not only has protected my system but has cause a large step forward in sound quality for all the pieces in my system including my power amplifier . It is a Richard Grey product . if you can audition one of their products do so . By what I've read they don't always work for a better sound ( system dependent ) but when they do owners are extremely satisfied . Take care .

I also bought an HTS 5000 when they were new. I remember hooking it up and noticing a definite improvement in the sound. I was living in an apartment at the time with a mid-fi set up. I currently have a bedroom system plugged into it- Sony TV, Sonos Beam and Sub, etc. It's still working. 

Back in the day, Monster Cable was revolutionary with their thick speaker wire at $1.00 per foot. I also still have some of their M-Series cables which were pretty good, but they don't compete with AQ for sound quality. They do hold up better over time, though, as they don't fray and their outer casings don't pull away from the tips.

I had the largest unit Monster made don't recall the model number but it was almost 100 lbs. Had a large red LED display, it  was in my opinion a glorified surge protector. If you got a power spike it would in most cases save your system but fry its self. When you called Monster they said well it did what it was supported to do save your system. When I told them it was now an inoperable paperweight they refused to service it. What they failed to tell you in the literature was it in most cases was a one and done.

A $30 power strip with a protection built-in would do the same thing.

I have owned a PS Audio Power Plant 15 and now a 20 provides excellent CLEAN Power.

Many surge protection devices sacrifice themselves to protect the products they're connected to - it is an industry standard practice.
Regarding sound improvement - there are many devices at many price points available. Different homes usually have different needs, so different power supplies many work better in different homes.
After trying MANY, we purchased a $20k Sound Application power conditioner. The difference it makes is not subtile.

I'm using a Monster AV2000 and HTS5100 in main system, a HTS2500 with home theatre, and a HTS1800 for bedroom setup and have used Monster for years with no issues. My 5100 packed it in one time and Monster was quick to replace it. They have done their job in my opinion.