AFAIK, any UPnP control point will play whatever your server knows how to handle – you don’t have to worry about whether a CP can play high-res PCM or DSD as long as the server does so. That said: mconnect is decent overall but has a couple of annoyances, chiefly the fact that it requires you to reselect your server (library) and your renderer (Bridge) every time you start. The regular version of mconnect is free, although there is an HD version that costs a few bucks and gives you some extra features. I also like Creation 5 media player; not free, but I think they have an ad-supported version also. You can really use any CP for comparing the sound of the Aries and B2, even the old, ugly, yucky-interface (but free) PlugPlayer.
I’ve never used an Aries, so I will be curious to find out what you hear. B2 fed by MinimServer is awfully good.
For a long time I heard about how good BubbleUPnP is but resisted buying a second tablet. Finally my local office supply store had a very attractive sale on low-end Android tablets and I bought one (hardly any battery life, but what do you expect for the price). BubbleUPnP really is the best of all those I’ve tried; definitely recommended if you decide to stay with the Bridge. I now wish I had spent a little more for better screen and battery.