Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Does this receiver support Sirius/XM ?  It doesn't mention anything in the specs.
Document: The update takes about 15 minutes. I only found the update by going to Yamaha's website. The receiver will not notify you that there is an update available. This update (180) fixed the following issues:  eliminated drop-out issues when Airplaying non-native music sites (i.e. anything that isn't Pandora, Sirius or Rhapsody) from the Yamaha iPhone app (no more drop-outs! ), made changing the volume smoother when using the Yamaha iPhone app.
This is my second Yamaha receiver. I upgraded to this one since it had HDMI ports in the back. My last receiver did not. It only had component and S-Video ports. When I bought this receiver I did not know you could down load the Yamaha app and control it from your iPhone (this is totally cool and unexpected). I like the net streaming of Pandora and Sirius XM.
Internet access through your cell phone provider wont do it, unless thats what your receiver is piped through. Took me about 15 minutes to figure that out.I haven't had to deal with the sustomer support.I cant say anything bad about this box, because my expectations are realistic.Last FYI - I paid this same price, pre Thanksgiving and Christmas (2012), so prices are holding. That should tell you something about this electronic device.
My advice to you: think about all of your wants/needs in a receiver, and really read the specs and reviews carefully to identify which models deliver on all of your requirements.
This receiver replaced a RX-V997 purchased in 1998. The specs on this unit are on par with the old one but the product was glitchy out of the box and had to be exchanged for another unit. I question the overall build quality of the Yamaha line now. When it works, I love it. Here's hoping the replacement works properly out of the box.
See my system specs below.....55" Vizio LCD 120hz 1080pYamaha RX-673 7.2 channel receiver networkedParadigm Monitor 5 front loudspeakersCC370 Center Channel speakerADP 370 SurroundsPW-2200 12" SubwooferSony PS3Directv HR24 HD-DVR networkedBoxxee Box
I replaced my Sony Receiver with this Yamaha unit because of the HDMI connection , iPod connection and controls simplicity. My old Sony had more buttons an switches than the lunar landing module which was very annoying, not to mention its control  remote was idiotic and crazy.
I can access my pandora, sirius and music library on my computers in my house.Apple airplay works like a charmJust found out I can hit the receiver from my laptop just using the IP address. Allowed me to setup my SCENESconfigure volume and tone setting.7.2.....7 speakers and two subs....second sub made such a huge difference in the quality and richness of the sond.Dollar for dollar best buy ever!
5 HDMI in1 HDMI outI'm not an audiophile so I can't speak to it's tech specs. I have an Xbox 1, and cable box connected via hdmi and everything works fine and as expected. The mobile app is nice to have although limited in functionality.WARNING!!!! This is a 2-zone receiver but ZONE 2 DOES NOT ACCEPT ANY HDMI INPUTS!!! I confirmed this with Yamaha customer service. It seems simple enough, when cheaper receivers have that option but it doesn't exist. Buyer beware
It now powers the living room and sounds great.The major improvements of the Rx-V673 (which powers the den) in my opinion are: (1) network connectivity and (2) Airplay. The receiver is hardwired into the network and can access anything on the network. This allows the receiver to be wireless controlled by an Iphone or Ipad on the network.
Answer: I own this receiver and can confirm that it does support SiriusXM, Pandora and Rhapsody after you update the firmware (it takes about 15 minutes via USB, the preferred way to update the firmware).