Does Sub Mini materially improve Era 300 mid and high range?

I would said poorer quality content you need to go into the sonos apps to bump up or adjust the EQ and increase the volume so it sound better to my taste. Honestly, this is back to your personal preferences and is budget a concern as well. Example for me personally, I like music or movie with good bass(good quality). I would conclude for music itself the improvement with sub mini is like 20-30% better, but for movies is like 50%-70% better for overall experiences. But would recommend you to try it out with sub mini if you don’t like it I believe they have return policy. Because I tried listening to music or movies with good bass before(which i prefer), so to me era 300 pair the bass does not satisfy me “enough” so in the end I get a sub mini. Hope I answer your questions. 

Making comparisons harder, different quality streams may be from different masters/mixes so you aren't comparing just the speaker  but the mix.

Serious testing would be to pick an excelent hi-res track, make several lower quality copies and then compare them.

Same for comparing streaming, analog and Bluetooth reproduction, you need an identical source stream to get valid results.

I really appreciate the discussion. And I agree with everything that has been said. Budget isn’t a massive issue but if I wanted wireless hifi I’d have needed to pony up for LS50s plus a sub. So that’s £2.5k including stands. Very happy with the compromise at £700 for the Sonos. Just wondering whether they’d get closer to the Kefs if I introduced a sub. That’s really the question I guess. But I think I’m going to have to try it. TBH, I don’t expect the sub to elevate the 300s enough to be worth the £330 but the curiosity means I think I need to give it a try. There’s tons of bass. Too much really. I just want sharp mids. And that may not be obtainable at this price point. I just don’t really want to add something which makes the balance worse. 

Well anyway I did buy a sub mini a couple of weeks ago. Only tried with music. 
 

it does improve the sound. There’s no doubt about that. It’s hard to describe how but there is slightly more clarity in the treble. A fuller sound. Not drastic. I can see why it’s difficult to describe. It’s subtle, but I could sell it for more than I bought it for and I wouldn’t want to be without it now. So worth the cost  

I do think you have to be careful with settings and the sub does make that slightly more difficult. But if you can find the right levels it is a noticeable improvement. I agree “materially” is not really a suitable word in this context. 
 

Downside is that my earphones now sound very light. So another indication that I am hearing lower frequencies. 
 

Anyway, thanks all. 

Tengo un Era 300 en el dormitorio con un Subwoofer 3.
Tuve varios meses el Era 300 sólo y no tiene buena respuesta en agudos aunque los bajos sí son potentes.
Hace un mes le he integrado el Subwoofer 3 que usaba en el salón y la música ha ganado en cuerpo pero los agudos no han mejorado, tal vez un poco pero no lo suficiente.

Estoy pensando en comprar otro Era 300 para hacer un par estereo con el Subwoofer y ver la  respuesta en agudos pero me temo que va a ser lo mismo.

Creo que los Era 300 tienen un problema de diseño con los agudos y que no se puede solucionar. Ya se ha actualizado muchas veces desde que salió al mercado y sigue teniendo el mismo problema.

Suenan muy bien sobre todo el Dolby Atmos que sí consigue agudos medio decentes (Apple Music desde la App de Sonos) pero la mayoría de música es en stereo y se echan de menos más agudos.