Well I managed to pick up a mojo/poly combo going cheap in the 618 sales (big China mid-year sale), so decided to go ahead. Thanks to everyone who replied earlier about tips etc on how to use it and their experiences with stability. This might be a bit of a long post but I thought I'd share my newbie experiences.
I owned a Mojo previously for about a year, but sold it around early 2019; mainly out of curiosity for what else was out there. Since then I've owned too many DAPs, and wondered about coming back to the Mojo. So for me on round two even Mojo alone is still very impressive - especially hearing it now with Audirvana & my favorites the B&W P7s, neither of which I had last time I owned Mojo.
I actually only really intend to use the Poly to playback via microSD card, and as it looked way simpler than stacking the mojo, which was always a bit awkward as a solution. Maybe later I'll explore it's other features.
So how does Poly stack up for me? Most important: sound quality is great. I feel that the rumours are true and Mojo+Poly from microSD card does give a bit more detail and fullness to the sound, drawing you in a bit more to a more lifelike sound.
But I have had a few teething issues and it has taken me a while to get set up and running well. I've been using Glider and Rigelian. I know Glider isn't being updated but I thought I'd give it a try after not liking Rigelian that much. Initially I had problems indexing via both Glider and Rigelian when attached to Wifi, and found that hotspot with hybrid mode gave the best results for Glider/Rigelian to read the card contents. For some reason now indexing is okay today with the wifi connection though. There's a few things like this where there doesn't seem to be any clear reason why an error was happening or why it's now resolved.
Likewise, it took me about 10 minutes to get it working today. The first day I had it (a few days back) I ran both Mojo+Poly all day until the battery was fully decharged, so left them charging overnight (unplugging them the next morning). I didn't end up using them at all yesterday then today the batteries were fully decharged again. I know Poly drains battery slowly due to the processor always being on, but that was disappointing. Even after connecting them to a charger, and being able to power Mojo on (and with both Mojo and Poly LEDs showing charge) I couldn't get Poly to connect intially, and then play once connected. Seems like Poly needs some power in battery reserve before being fully functional? Which could get annoying if the decharge during non-use is large; makes it less of a grab-n-go solution.
Glider vs Rigelian:
* I prefer the look and UI of Glider. Partly as Rigelian can't read artwork off the microSD card and pulls it off discogs etc, so I've ended up with some pretty random band/artist images. It seems from the Rigelian documentation if Poly were updated to a newer MPD version then this problem would be solved.
* Glider works well - BUT, there's a small clicking sound which happens 8s prior to track changes then again 8s after. I remember reading somewhere that it switches between MPD and UPnP in order to manage gapless, so maybe I can hear something happening in the switch. A few times I have had other weird behavior like the end of tracks or start of the next track being clipped. Also with Glider, it seems there's no way to select the output first - you have to play something, half then time it seems to come out of my iPhone speaker, then I have to switch outputs to Poly.
* With Rigelian, after my phone has gone to sleep and I wake it up, Rigelian shows Poly as disconnected (even when still showing as connected via wifi on iphone settings with hotspot). This confused me at first but after a while I realized that after waking the phone, it takes about 10 seconds for Rigelian to recognize the connection with Poly. This means that, e.g. if you want to stop play or switch tracks, it can take a while to do so. Even worse is when actually the wifi signal is dropped - Poly keeps playing so you have no idea. Then you try to stop play, pick up the phone and wonder why Rigelian is taking so long, only to realize the phone isn't connected to Poly via wifi anymore. In the meantime, you can't control Poly at all.
* Rigelian sometimes has random errors like you click on Artists and it comes back as blank saying "No Artists", you have to go back to home page, select Artists again and it comes up with an Artist list. It's like it drops the info/connection with Poly sometimes.
* With both Glider and Rigelian there is a delay of a few seconds between starting/stopping play and the change being transferred to Poly. Combined with above point it can mean 15 seconds or so to stop play.
So yes in all, it's great when it works but does have it's niggles.
Hardware-wise I would have loved to have a direct microUSB audio in still available on the outside of the Poly too, to use Mojo as a DAC without having to take Mojo/Poly out of a case and disconnect Poly.
Software/UI-wise, if Chord are still watching this thread some suggestions for user improvements are:
* As others have said, I think it would be handier if Chord could build a simple music player in order to avoid third party apps, hopefully to be snappier and with less delay than other apps.
* Wi-fi connection during set-up: it would be useful to have a prompt/info piece during the wizard that if Gofigure is showing no wifi connections, then changing country wifi region in settings may be necessary. Being in China I had to go into settings to change region first before I could get a wifi connection working - mainly because I remembered seeing the region settings in the manual that I'd read beforehand. A small prompt on the set-up screen would help avoid confusion - or as an alternative, just make it so you select your region in Gofigure first when setting up a new connection, then connect to a wifi network. Many users are out of UK so that would help with international set-ups.
* In GoFigure it says "Update Left Card Database" - I'm guessing this a typo meant to say "Update microSD card database"?
* In GoFigure setup, when you are initially asked to set a Wifi password for Poly's hotspot you should have some info upfront as to what the password requirements are. I got "illegal password" error. I have some (very limited) web design/support experience and from a software/UI perspective I think people are trying to weed out unhelpful tech-geek messages like this - (a) it's not illegal, there's no law against it, and (b) it's just not a very friendly message. You want to be friendly to users, so let them know how many characters etc. the password needs first, then if they still put in one that doesn't match the requirements also change the error message to something nicer, like "please choose a password with 8 or more characters" or whatever it was.
* Also in GoFigure there's quite a delay between when you hit "Device info" and the screen updates, and there's no indication the software is doing anything or has registered a click/tap. It looks like GoFigure has frozen during this time. You should add some in-progress style icon or something to show that the device info process is working/underway.
* Device firmware update - I had to update to 2.03 first and then 2.04 came up as an available update and I went through the update again. Is it possible just to skip to the most recent firmware? Particularly for a new unit it is an issue as it could be a few updates behind by the time someone buys it.
* The Poly manual is not text-searchable in adobe. Is it just images? It would be better to have the pdf manual searchable in a pdf reader.
Other random thoughts:
* I'd forgotten just how toasty Mojo gets. I feel like it's even more with Poly connected.
* I wish the cases were cheaper, especially as you don't want to move it too much without one
