I have a pair of Eris 3.5 and love them ! I use them to replace a Panasonic 90's black plastic stereo which was wired to my office PC. That did good service to listen online for many years.
I planned a little project where I thought I might sit out in the garden and quietly make music out there under a gazebo. That plan never came to fruition last year so I use them for internet music playing mainly.
I bung the the ports on them with old rags and that I find creates a better bottom for me. It's much tighter sounding. The side walls on those speakers make a hollow sound when you tap the side, at a guess 4mm thick mdf. I was not impressed by that but for the money I don't think there is anything better.
I also upgraded that extremely thin piece of wire connecting the satellite speaker from the amp to a nice thick piece bit of copper cable. It was so thin I did not like the look of it.
Believe it or not they alerted me to a little sonic problem that I had not heard on the E8. It may be they have an internal resonance (or where they are positioned which is not exactly ideal) on a harmonic which was purely coincidental. I was playing a the last track I made and it showed a bass note an octave up as "sticky outty" which is my non technical term for such matters
and yes my BM6P were in agreement come mix time. Though this was more pronounced on the Eris 3.5 so I suspected a coincidental internal resonance from the bunging.
What I especially like about them is a metal tweeter guard, that's great and also tone controls, very few speakers have a tone controls and I dip the top end off slightly for taste. They look nice too.
Of course they are a tiny speaker and you cannot really make detailed decisions on them. They are a VERY good multimedia speaker and at a pinch... well... a snare sounds like a snare, a kick like a kick. You can use anything to mix on but do you want to is the big question ? Choose you gear commensurate for the task at hand.
I also use Eris E8 (also port bunged) and use those in an untreated room and up very close and with fairly low volumes. So I hear a ratio of more speaker than room. They still have a satisfying amount of bass this way without the low end flab which would be too much even monitoring very close. They end up being about 12-14 inches from my ears and I can go as close as 8-9 inches. I monitor quite low of course due to proximity so they have had an easy life power consumption and driver wise. I do turn them up and walk around the room / stare out the window perspective from time to time.
They are plenty loud.
This seems to work well for me. I like these Presonus speakers for their unbeatable bang for buck. I have no connection with them, just like the way they do things. I like the tweeter guards given my cat often helps me play keyboard by sitting on it and coming up to the speakers. At the time she was a kitten and the tweeter guard was handy.
I bought the E8 in 2016 with a 2 year extended warranty which was not needed, faultless since 2016 till now for £324.00 very good value.
I cannot grumble and would buy more of them for my existing and continuing needs outlined above. And I suspect they have only improved things since then.
with my biggin up ere Eris 3.5.