I have not ever used one but in general terms a PCI or PCIe card will be able to reach lower latency than a firewire device. Some of the best firewire devices do achieve very respectable low latency but the bulk of what's available not so much. Tascam would likely not be the cream of the crop in this regard.

Additonal factors may be the chipset of your firewire card as well as the bus assignment of the firewire card.

thank you for the reply!

I have come to understand this by doing some further reading on the topic now.
I think I will start using it as only a DAW controller in cubase, but I still want to upgrade my soundcard so that I will have an external box with controllers and a headphone output.

How much do you think it will differ in latency if I buy an external usb card?
I'm into buying the ESI u46 XL.

I don't want to get dissapointed after I have ordered and tried it at home and then notice a higher latency than my audiophile 2496.

USB is no good for low latency. No good unequivocally.

I have a PCI card for my home desktop and I use the Fireface 800 as my mobile interface. The FF and a good computer properly set up is pretty low latency but still can't beat a tweaked desktop with good PCI card.

If you are not mobile and really desire low latency look into something like the RME HDSP 9652 or other PCI card.

thank you

it's strange that most of the soundcards on the market now are usb cards. I can understand that pci still is the best low latency choice for non-mobile systems, it would have been nice to have more to choose from, more cards with breakout boxes like the EMU 1616.

I will look into the RME. thanks!

Niclas