Hello folks, I am new here. I own a Yamaha Rx-v663 Avr and since it lacks a USB port and neither does it have any Lan ports or wifi, I have been living with the belief that this Avr can never be upgraded. I really wish I could upgrade the chips in some way so it starts to support HDMI 1.4 and maybe I get to use the HDMI ports as ARC ports at least. Really I am in love with the tonality and sound signature I get from this Avr. Maybe my ears are just used to it too much. So dont want to sell it just for the HDMI port upgrade.
But I recently noticed there is one mysterious port on the rear panel right next to the hdmi out port, without any labels to indicate what it is. Neither could I find any info about it anywhere on the Internet or in the user manual. Please see the snap attached and can someone let me know if you know what this port is for? I am just getting excited by the thought that what if I could upgrade the avr through that port in some way...
Thanks much in advance.
But I recently noticed there is one mysterious port on the rear panel right next to the hdmi out port, without any labels to indicate what it is. Neither could I find any info about it anywhere on the Internet or in the user manual. Please see the snap attached and can someone let me know if you know what this port is for? I am just getting excited by the thought that what if I could upgrade the avr through that port in some way...

Thanks much in advance.