For a while, as the opportunity has arisen, I've been testing different multi channel USB sound cards.
Generally the multi channel sound cards sold are intended for use with programmes such as "Traktor" and so expect to produce a mixed output for the audience and a headphone pre-hear output for the DJ.
Hence USB sound cards like the Numark DJ IO or the Reloop Play have two stereo channels presented on phono sockets and one of those channels also on a headphone socket.
For PlayIt Live, in my view, the ideal setup allows for three stereo channels. These are "now playing", "next to play" and a cue/QuickCarts output.
Also, in an ideal world all three stereo channels would be presented on phono (AKA RCA) sockets as that is generally what mixers have as a connection and they are reasonably reliable.
The search for the perfect USB sound card lead me to ESI. They seem to understand the likely requirements and have made various cards with three (or more) stereo channels.
No longer widely available new but sometimes to be found on ebay, the ESI U46 (various versions available) is good. The U46 also has 2 inputs (intended for turntables with timecode vinyl but switchable for line level) and (critically) drivers to support ASIO and various operating systems.
I had some driver issues with the U46 (the newest one didn't seem to work under Windows 7 properly) but I found one that did work and the U46 works well with PlayIt Live. The U46 is powered via USB (no extra PSU "brick" needed) so ticks the boxes.
I have a laptop which I use with various music software (primarily Mixxx and PlayIt Live) and the U46 is a bit big to slip in a laptop bag so I was looking at other options.
If I were buying a new USB soundcard for a "static" setup, of the current USB soundcards, I would probably go for the ESI Gigaport HD+ which has 4 stereo outputs and sensible headphone options however that was a bit more than I needed.
The more compact option is the ESI UDJ6. This has 3 stereo channels out (no inputs). One stereo channel is on a headphone socket (the 1/4" size) and the other two stereo channels are on phonos.
The current ESI drivers downloaded from their website installed and worked first time on my Windows 10 netbook. There is a "helper" console with the software that allows level control (useful for headphones and PlayIt live) and the display also shows bargraph meters for each of the channels.
All in all, if you can get the UDJ6 (new or second hand) at an acceptable price I can recommend it for use with PlayIt Live. Definitely an 8/10 (having the headphone output also on phonos like the Gigaport HD+ would have got the last 2 points !).
I've now got hold of the ESI Gigaport HD+.
This is very similar to the UDJ6 but physically larger and with 4 stereo channels out.
All 4 stereo channels are available on phono sockets (8 phonos) and there are also headphone sockets for the first pair of phonos (1 & 2) and the whole mix (1-8). These are probably less useful in a PlayIt Live application.
As expected, the device gives 4 Windows audio devices.
Rather nicely, it also has LEDs that show audio which is very handy while getting all the cables and channel configuration right.
The latest Windows 10 driver seems to work well.
There is only one issue, a curious warning at PlayIt Live startup which I need to investigate, but it works well.
In my application I use 2 players, an output for Quickcarts and the final stereo pair for the prehear.
These go to 4 stereo mixer channels although the last one is never faded up.
All in all, this works very nicely.