For some reason I cringe when I hear this as an opening statement...but your post is very good and very honest.

A better enhancement for F14 is a used flea market external sub - if you like explosions.

I know this thread is old. ... but wanted to mention that I've used a Speaker Line In to RCA level converter (https://www.amazon.com/dp/B07S8W7BRQ/) along with an old 5.1 surround amp to do some fairly ridiculous sound improvements. I'm talking about Bally / WMS DMD games and DE/Sega/Stern only here although this would work fine on anything previous to Spike and JJP I suppose.
I kept nothing in game - literally moving the sound completely out of the game with small satellite speakers on stands and pointing to the player and a big booming powered sub on the floor. The amp took the mono signal and created a surround simulation likely based upon the frequencies coming into it. I tweaked the amp through all kinds of timing delays, echos, and presets. I re-positioned speakers until I felt like it was the most immersive. When connected to TRON - it was nothing short of amazing. LOTR the same. It was good enough to remove the stock speaker connections entirely and just let this amp and speakers take over. With a lineup in that room of 18 machines playing a tournament with a lot of games around the player, each person mentioned that TRON was the clearest sounding game among the lineup - and only the sub being disruptive. This was due to the speakers being very directional and pointed at an average person's right and left ears. The drawback was rear surrounds which were not triggered enough by the amp's simulation to earn the mess of wiring required to put them behind the player.

So this mod cost me about $10 for the line converter (really $0 since I already had it) and using recycled old surround sound equipment that I couldn't sell in a garage sale for $50.

I have to disagree with this post..... While I don't think the chage is huge I do feel it makes a difference.

I personally never buy the high end kits . I buy the least expensive one . I think they are like 80 buck from FF. All the back box speakers are the same which is what makes the most improvement.

I pick and choose the games I put them in and IMDN, AC DC, and Met will all have them in eventually.