Bypasssing dsl modem

[parad0x0n]

Hi!

I've been just wondering, that if there's any way, not to use modem completely,
but to use pfsense as a modem/router/firewall combo?
I know, that you could just set up a modem to bridge mode,
but I don’t really get, why can't we just use a standard patch cable, to pull the rough DSL line in, and then use pfsense as a modem too.

The problem is that, I'll want to build a mini-itx pfsense bulild (motherboard comes with 1 pcie) with a 4 port ethernet adapter.

Since I'll be using server grade adapters, and good quality cabling I'd feel guilty to put a cheap (there's no much good dsl modems on the market, last time I checked) modem as a bottleneck, between the fibre pro unlimited, and my custom psense build?

Cheers.  :'(