How much does string thickness matter?

It's all about tension. You can theoretically tune any thickness of string to any note. But thicker strings will be tighter than thinner. Sets generally are made to have relatively similar tension across all the strings, but some folks like some variations, so you can get sets that have more tension in the lower strings, for example.

It makes way less difference to the sound than most people think. In a blind test with different string gauges, I think few people would be able to tell which is which.

Also be aware that changing string gauge also changes the tension. You will need to readjust intonation, spring tension (unless you have a fixed bridge), and possibly truss rod.

For a beginner, I would highly recommend sticking with the standard 10-46. Aside from the adjustments needed, heavier strings are also a bit harder to play. Even as an experience player, I find zero benefit of heavier gauges.

Play whatever is most comfortable.

Rick Beato did a detailed breakdown and tests on string weights…turns out breaking your hands to play .13s doesn’t get you any sound advantage.

String thickness is kind of personal preference. Thicker strings won’t give you different notes but they will sound more pronounced than thinner strings.

I find thicker strings really come into play when you’re doing alternate tunings. Especially drop tunings like Drop D, Whole Step Down, Drop C, etc. This is because when you loosen thinner strings for those lower tunings the notes won’t ring clear because the strings will be super loose and buzzy. Those tunings really only come into play for playing heavy metal. Some “metal” guitars are specifically set up for those lower tunings too.

I believe Steve Ray Vaughan was also rumored to play on .13s (.13 being the high E string thickness). So again thickness is kind of personal preference unless you’re doing low tunings. I think most people use .10s like you do.

9-42 is typically for fender scale.

The width of the string has changes to the intonation, but that is is fractions cents off going from 9s to 10s. It is more about player preference and getti g a string to not flow arounf with how hard you want to pick and how it feels. In e standard on a 25.5 scale you could go all the way down to 7s or up to 13s.

I really like 9 or 9.5 to 46 on fender scale

String thickness will get you the same notes on the same frets, when tuned the same, but it will give you a slightly different tone.

However where thicker strings really come in play is drop tunings, such as D standard, C standard or even lower. If you take a set of regular slinky strings and tune them down to C standard they lose all tension and become seriously floppy. This impedes playability and makes the guitar very difficult to tune this low.

But slap some thick strings on, I use 12-56 for C standard, and the guitar tunes just fine and it retains a somewhat comparable string tension to regular strings tuned to E.

It'd be best to try a few sets for yourself and feel the difference.

Personally I don't care about tone and I'm not of the opinion that you get much better tone with heavier strings (as some people claim) but string gauge is important if you do serious down tuning (I mean more than half a step) because the strings will get floppy and that'll make playing a bit more weird/difficult if the string is flopping all over the place.

If you're not tuning lower than standard E maybe try a lighter set next time (than the 10-46 you mentioned) and see how that feels. It should feel much easier to fret the notes and do bends.

@RageAgainstTheSurge
Other posters already covered it but yeah, in standard tuning string thickness might give you a very slight, barely detectable difference if any at all. Thicker strings only matter when you're playing in alternate tunings, and even then you have to tune quite aways down before regular strings hit their limit and become too floppy to use.

Outside of that? Strings aren't meant to last forever! Try several different types and find what you like!

I've seen some sets that have heavier bass strings and lighter treble strings. I think the idea with this is you get the benefits of sustain and fullness in the bass and the ease of bending the high notes.

But I think it can be hard to hear the difference. It's probably mostly about comfort and preference.

This isn't really what you asked, but if you plug your spark go's headphone jack into a set of bookshelf speakers you pretty much have yourself a much bigger and nicer sounding practice amp.