Noticeable step up from my DH-75 Silver Sonic...

Also, my Cambridge Audio sound dock has XLR output as well as rca coaxial... Should I use the XLR output instead of my rca coaxial to go to my Bifrost Dac coaxial input for my digital? I don't know if I would gain anything by going from XLR out to rca in, so that's why I'm asking here... Any help is always appreciated...

To answer your question about the XLR connectors, I wouldn't worry about it unless you have fully balanced equipment. Stay with rca.

To answer your question about cables, I don't think its a smart move. Your DH75 is overkill for your equipment. Not only that, just setting a $300 budget is foolish. Go by sound quality, not price. Look at your system in context. Do you really think a $300 digital IC is a better move than upgrading an active component that will have a much bigger effect on sound quality? You're only going to get so much out of your NAD. I would start there. Your amp allows you to jump the amp and preamp sections externally using rca jumpers. I say put the money towards a better preamp and plug it directly into the amp section of you NAD. I don't care how expensive the cables are, theres no way they will make a bigger difference than upgrading an active component.

Agree with Zd542, the DH-75 gets good reviews, and should work well in your system. Also, digital XLR is 110 ohm and digital RCA is 75 ohm. I’ve seen digital cables with XLR on one end and RCA on the other, but that just makes no sense as it would seem to result in a mismatch of impedance.

When it comes to cables, patience is a virtue. Too many people get caught up in spending more than they should, when upgrading a component makes better sense. Cables do make a difference, but sometimes it’s only that, different, not really an upgrade, but we think it is because the cable was more expensive. Some years ago, I rolled speaker cables on a $5000 pair of speakers, and ended up using a $400 pair, just better overall sound than a $3000 pair from a well respected company. And not just me, several audiophile friends agreed.

Zd542 makes a good recommendation to upgrade the preamp, but if you don’t want to add another component, save the money, and later, just upgrade to a better integrated amp.

If you care to share, what does your system do well, and what needs improving?