Any affordable intergrateds known for huge sound?

For the same money as the Plinius at $2k-$2500 you can get a MUCH MUCH MUCH(yes indeed MUCH!..) better sounding, world class even Musical Fidelity integrated that is absolutely gorgeous sounding! The piece at around $5k new is the best integrated I know of...and I've heard a lot of em.
For cheap, try the Jolida 502b tube piece.
Although, what speakers are you using?

I have enjoyed both of my Krell KAV 300i integrateds. They go for around 1100 used and through a variety of Sonus Faber speakers have done a fine job for me. With a Synergistiac Research power cable you can even kick it up a notch when you are ready to.

Jolida has a brand new integrated I heard last night with a pair of B&W N805's. Great sound. Fully tubed with 100 wpc and some really decent bass. $1695 brand new, but we all talk the salesman down at some point. The Plinius, from what I have heard is an excellent piece. Also the Krell I know is quite powerful and can throw a nice soundstage, atleast when I heard it.

Try Redgum, I also second the Plinius 8200mkII.

I have owned the NAD C350 and also ARC Complete. The NAD actually replaced the ARC Complete. Still I felt the same as you do. I then went back to tube separates. Bought a Quicksilver LS pre and AMC CVT-2100as tube amp. Both of these are "hybrid" designs using both tube and SS. Spent about $1300 for the two. (both were new, but the Quicksilver was an "open box". The difference between these and the NAD was fairly significant. This is not meant to be a criticism of the NAD, which is an excellent amp for the money but the tube separates are in another league. Much bigger soundstage. Lush, airy sound, little or no grain. And this is with speakers placed about 6 in from rear wall and cheap cables.