If the 2 channels of the Apollo Twin X are too few, don't worry, you can add more, up to 8 without having to change cards.
To do this, you need an external converter, preferably for a convenience and cost factor, with the preamp section already. There are many models on the market, but if you want to have everything balanced while maintaining the UA sound, you can buy Universal Audio UAD 4-710d.
Alternatively, you can use an external preamp and a separate converter, as in my case. I have a converter of 2 channels RME ADI-2 and external interchangeable PRE for the type of stamp I want for my productions.
By making this type of connection, the sound is converted and made available to the Twin card via ADAT. Next, we will need an optical cable to connect the converter output to the Apollo Twin's ADAT input.
The most important thing is to click on the console, in the section dedicated to clock, where by default it says “INTERNAL”. By selecting “ADAT”, you are going to tell the sound card to synchronize itself with the clock of the external converter. If by chance the word ADAT flashes red it would mean that the converter and the card are not synchronizing correctly.
WARNING: the fact of selecting 44.100 Hz on the card with internal clock and 44.100 on the converter is not sufficient for synchronization, even if the sample rates are the same. In this case you will hear the sound coming from your external preamp as if it were “robotic”, this is the result of a non-synchronization of the 2 devices.
If you have an external Pre and an Apollo Twin it is preferable not to connect the Pre output to the Apollo line input, as the Pre of the card would add up to your external Pre. For this reason, I decided to use my external preamp via a converter to increase the channels of my card from 2 to 4 while preserving the sound quality.
