Add a pre-amp to Mola Mola Tambaqui?

How do you know the Tambaqui doesn’t sound “digital “ if you never heard it?
TMR will take it back if you don’t like how it sounds. Not all local dealers will offer this benefit

I heard it but I don’t own it

i have friends.... i would just go to the same place he bought his except he bought a used unit and i cant seem to find one..

i check this website every day and never see it drop on the market

Here’s a used one. You can workout out a deal. 
https://www.usaudiomart.com/details/650010344-mola-mola-tambaqui-streamer-amp-dac/

I owned a Tambaqui for a short while until a few weeks ago.  I liked the sound better when using an outboard preamp.  I also played with the output voltage, which you can do through the app but I cannot remember which setting I liked best, maybe the top position (6V?).  

You should definitely call them but I believe TMR is actually a Mola Mola dealer.  The only way you will be able to answer these questions is to try one for yourself with/without an outboard preamp, and trying the different configurations in your own system.  Below is the return policy posted on TMR's website - a 60-day trial is hard to beat IMO.

New product lines for which TMR is an authorized dealer carry a 60-day satisfaction-guaranteed return policy. Return shipping costs are at the expense of the customer unless the product is defective. Full manufacturer warranties are in effect for these products.

thanks for the leads