There’s a lengthy thread about this, probably poorly named. The most important post is the first one:
TL:DR, Sonos is working on a fix.
@Airgetlam I saw that, that mentioned home theater setups, I'm talking non home theater set ups. Sonos mentioned it only affects what posted in that thread.
Ah, my apologies.
There’s no reason why, after (or without) running Trueplay, that you can’t make adjustments to suit your personal music and listening. Trueplay is just an engineering solution to a potential problem, it won’t match every single person’s personal ears.
@Airgetlam Why does Trueplay make it feel like the bass isn't as heavy even when we adjust Sub Audio? Do we also need to do the bass EQ settings afterwards?
All sound is subjective. The algorithm that was written by Sonos was designed to do as much as possible, I think, to mitigate poor speaker locations and provide as “flat” or “normal”, whatever those really mean, a sound to the user.
You should always tailor any sound system to your desires. I don’t think I have any, including my Sonos, that are set to “flat” as they come from the factory. I’ve tweaked each one of them for the environment (like my convertible) and the speakers. It’s likely most people don’t need or want to adjust after Trueplay, but there’s nothing wrong whatsoever if you do. Trueplay isn’t “perfection”, it’s as close as they can get to a programmed “ideal” as defined by something other than your ears.
It’s your system. Modify the sound properties to your ears, your musical style.
What true play does where a Sub is in the mix, is get rid of bass bloat so that the result is a tighter sound that is more natural - especially for acoustic bass like that from a base guitar. If you are accustomed to bloated bass, at first the tuned sound may appear to be lean. Once you get used to it, the bloated version may sound loose/flabby, overpowering the mid range from the speaker pair.
Which isn't to say that a personal preference for the latter is wrong; it is just that one should try the true play tuned flavour for some days and then toggle back and forth to see what is preferred, and then stick to that.
In my case, for my Play 1 pair+ Sub, after trueplay, I had to dial up the Sub level by 2 points from the default central position, but I found no need to change the bass EQ setting.