Amazon abilities but with digital output... Sonos?

Not sure what Big System Means?? Are you trying to connect physical cables? like a pair of RCA inputs? What Alexa device (Echo)? Normally you can connect the Alexa device via a 1/8 audio jack cable to RCA.

@dtximages  - As @mattmiller indicated you can use a 1/8 audio jack to RCA inputs cable with most Echo devices.  You can also use a Sonos Port for a Alexa controllable source, but at $450, it is a bit pricy.  Both Bluesound, through BluOS, and WiiM units are now Alexa enabled.  You could pick up an older used Bluesound Node or 2i for a couple of hundred bucks on eBay or USAudioMart and they have optical, coax, and RCA outputs.  A WiiM Pro (with the same outputs) is $150 on Amazon.  

Now, this all assumes that the "main" system is being controlled separately and can be set to default to the desired input and/or volume setting.  There are ways to use an Alexa compatible smart outlet to turning on/off an system.  I have done this with systems in my home as well has helped others to do it.  But I would need more info on the equipment of the "main" system and what sound quality is desired, etc.

- Jeff

From the Bluesound web site:

Bluesound now supports voice control. Amazon’s Alexa is the first voice integration for BluOS, allowing you to use your voice to explore music services, select presets, adjust volume levels, switch up songs in different rooms, or even group your Players together and play your music in perfect sync throughout the house. Simply connect an Alexa device to your Bluesound system and command your music like never before.

From WiiM website:

Easily build your multiroom sound system with your existing AirPlay 2 speakers, Amazon Echo, and Google Home devices. Using your legacy audio devices, you can create a more flexible multiroom sound system with multiple WiiM Pros, WiiM Minis, or Linkplay-powered devices. WiiM Pro supports multiroom from various audio source inputs, including WiFi, BT, Aux, and SPDIF input, making it versatile with almost every music listening option.

Thanks for the input.  I do not want to use the 1/8th output jack on the alexa as that uses its internal DAC and is essentially double preamped / double volumed when you connect it to the main system..

"Main system" just means my main audio system. Instead of logging onto my Eversolo app, I want to just say "alexa play elton john" and it comes through my main 2ch system which includes all separates and speakers/subs.

My experience with the Bluesound Alexa integration is awful. You basically have to add the Bluesound as an Alexa "skill" which is hit or miss and always requires signing out/in to fix it.

I will keep the system always on so no need for plugs.

I just want my streamer to hear my voice like my alexas.  You would think that would have already been done on the regular.