I'll try 7 - 3 - 7 and see how it goes. I've splurged a ton of money lately so upgrading the speakers atm isn't on my top list but it's good to know there are options.
Unfortunately with me, I've never done wiring of any sort so it's not something I'd be able to do, making a change more expensive but I'm more than happy to save here and there for a near future upgrade if need be
I waited a little while after I bought my car as it was quite pricey (by my standards) just to recover but...
A word of advice: do it now (budget permitting, obviously).
I upgraded my W203 after having the car for 4 years, I sat on the fence for that long..... It cost the same, but I had less years to enjoy my investment.
When I bought the W204, I decided that I either upgrade it shortly after buying it, or not at all.
So back in 2017 I let Comand UK loose on the car

and I have been enjoying the result for three years now
... I did the same here. My reasons were slightly different - I didn't really want to spend the money on the sounds in my AMG as I usually had the music set lower with the windows and sunroof all open so I could listen to the V8 soundtrack all the time. So wouldn't have been value for money and the stock AMG speakers were decent (HK speakers I believe just without the HK amp) and so I installed a subwoofer. That took me a whole weekend to do it properly and I still had to do a bit more to the sub mount I made.
Then I bought a CL but I knew very quickly, perhaps after 6 months, that the novelty for me was going to wear off very quickly and my suspicions came true after a couple of years of it. I did toy with the idea of upgrading on it but dithered once the doubts set in so I knew I wouldn't be making that mistake on the next car!
Then I bought my S500 and I was going to have a stab at it myself. However, whilst I am sure I could have done it, I'm Freddie Flintoff-shaped (tall and heavy) and where I used to gut and do ICE installs in many of my early cars in my 20s (transferring the same kit usually), nowadays I can't access and contort myself in ways required to access all the speaker locations. Not only that, I knew if I installed a sub that the speakers in the stock system are shyte so I would HAVE to replace those as well and amplify the whole lot properly.
Then it's know-how how to take things apart and accessing different speakers, wiring diagrams to tap in and running new cables, ensuring things are put back correctly and things like air bags are not interfered with.
Then it's time - if you work you perhaps don't want to spend hours of your time titting around.
So I decided to just get it done by a firm who do this sort of thing all the time and have the know-how which I am missing as it was 2003 I last did a full install, and from the AMG I knew, things have moved on.
So I involved COMAND after much research and 6 months later in Summer 2019. Richard and the two installers were immensely helpful and did a great job. Many a time we farted around with something else that needed doing but they did an honest job and Richard is immensely knowledgeable.
I wanted the upgraded sound system at the start so I would get the maximum enjoyment out of it and I knew I would be keeping my car for a long time all being well.
I didn't buy an AMG because I no longer trust myself and so I spent a fair few quid on the install knowing that I would be saving in running costs and not buying an AMG...
It took me a while to tune it how I wanted it as I have a very specific sound I like but once I got there - every time I use the car I play my own music and it sounds great.
Being an S500 it has double-glazing, a super-smooth ride and amazing build quality and so the experience is amazing.
So I would say get it done when you can do it...