Hello Travis,

Generally speaking most audio interfaces are going to sound sterile/clean as it allows you to alter the signal by choice versus being coloured on the way in. There are some exceptions however. Some manufactures do offer "enhancement" functions, but these so called enhancements can be achieved with other equipment or plugins (if that is your flavor) to arrive at often better and controlled results. Since you are using API style preamps those are known for their colourations alone, so if you want more that, then try hitting the preamps a bit harder as the case with analog, typically the harder you drive it the more flavor you receive. Also, I would recommend determining what non API style sound you are seeking before making any moves. If you like that sound then stay with it, as the Burl is not going to be much different and instead invest in a compressor. They can not only be used to control dynamics, but also as a colouring box either with minimal 2:1 ratio compression or in bypass mode. Simply running your signals through the hardware itself in bypass mode will impart some colourations. If you go this route ensure it is a quality compressor from a reputable manufacturer. If you are running the 500 series gear, then there are a lot budget friendly options available, especially in the used market. I hope this helps.

Cheers