If both of them stopped working simultaneously I would look into configuration/network issues.
I see a couple of paths you could take.
1. Buy an Oppo 103, it allows streaming music and has an iphone app(which I have not used) but realistically, it works best with a screen on.
2. Purchase one of the older squeezeboxes from Ebay, such as the Squeezebox 3 or Touch. I've got both of those and they work very nicely and use the same software you're used to.
3. Buy into Logitechs new UE Smart Radio. It has a headphone output which could be plugged into your receiver and it can run a crippled form of the Squeezebox server software called "UE Music Library". While it is crude, it should support your needs pretty easily and there is also an iphone/ipad app that I believe works with it. It does require a broadband connection at all times (not standalone like LMS).
UE Smart Radio - Wi-Fi Music Player & Digital Media Receiver - Logitech
I'm not sure what other competing solutions there are like Sonos. I primarily stream FLAC files from my home server so handling that in a high quality manner is my chief criteria.
good luck,
Jotham
P.S. If you are in the Apple ecosystem, then another approach would be something like an Airport Express. It can stream music from itunes on a computer to speakers. It also is a nice wireless solution.
Apple - AirPort Express - A powerful little Wi-Fi base station.