@dz13 that is some great feedback and fruit for thought.
I do think the OP's feelings about which brands to upgrade to are good thinking. After doing a little research and listening to a couple I feel an Innous will be my next step up. I've only been into digital streaming maybe 2 1/2 to 3 years now. I came into this media thinking all digital transports would sound the same. Seemed logical at the time, it's only transferring a digital signal and any jitter should be easily dealt with by any newer decent dac. Yet in my personal subjective opinion this doesn't hold true. I've tried upwards of 10 different "budget" streamers searching for the best SQ on the cheap. Most of them in that range do sound similar to me when used as a transport only..but there are differences in my opinion. Either in sound quality, darkness of background, or soundstage and imaging. Subtle differences in the budget category.
I'm familiar with the OP's Zen Stream. I've owned it twice now, both times giving it the boot due to the laggy and shaky software. The reason I went back to it a second time is I feel it has good SQ.. especially for the money. With LPS I liked it better than more expensive streamers I've tried. One streamer I've liked just as much or actually more is the Primare Prisma. I picked one up second hand and have been very happy with it. 5volt power supply that can be upgraded. I prefer Quboz as well and use Chromecast. I've used Chromecast in the past with my Cambridge CXN2, Arcam Sa30 & later with the ST60. I preferred the sound of the Prisma when using CC. Just my personal preference though, could be different for everyone.
I only mention this because if it is just the software of the Zen Stream you would like to change then a Primare can help in that regard with Quboz, but also keep the type of sound quality you are use to. Maybe a side move with subtle differences but I do like using CC now. Prisma has set backs though like everything. No USB. Chromecast is topped at 24/96khz. I found that to be no issue. Actually instead of going bit perfect native I upsample everything to 24/176 with the Prisma. Just sounds better to me..I dk why. No software issues though.
I've never tried an Eversolo or the Halo Red..a couple of the "budget/mid level" types that seem to get good reviews. I also think stepping up to the likes of Aurender or Innous, just to name a couple, will give you the upgrade that you are looking for. Or switching to Roon might be something you would like as well. Better functionality it seems...better than using the Zen Stream native app I'm sure. One thing that was already mentioned..make sure your Dac is up to par before buying a big dollar streamer. Unless you are looking at one with built-in dac. Good luck.