help on center speaker

no, I would set the NAD crossover at 80hz (all channels) and all speakers small. Turn you sub crossover all the way up or disable it. Remember LFE is 120Hz and lower, if your subs crossover is in the way you will be missing information. A large speaker never sends anything to the sub, only small below the crossover setting...

I will keep it at 80 hz and small speaker setting, until I upgrade my front speakers.

Remember that the Afekt is factory set to match the Unik. If you put it with a "larger" speaker with better bass response than the Unik, such as an Index, you may find the bass a bit tubby. This is what happened when I put an Afekt with Tukans. I had to adust the Afekt so that it crossed over at a point more appropriate for the Tukans (i.e. lower). However, if you do this, it will now not match the Uniks, which you also have. You might not notice it in HT, but if you listen to newer formats of multichannel music, such as SACD or DVD-A, it may not be a good thing . This is one reason why speakers all around should be relatively similar, and full range, as opposed to the days when rear speakers only produced effects.

Regarding one of your other comments about front speakers having to be be full range, they don't "have" to be. However, if you have full-range speakers, you will have bass in stereo. This gives good musical reproduction. And for HT, let the sub take care of the non-musical booms and crashes. If you have small monitors, crossed over at a high point, with bass filtered out and handled only by the sub, you will have mono bass. Fine for HT, but there's a lot of musical bass in the 40-80Hz mid-bass region. (The open E string on a electiric guitar is around 36-38Hz) It won't be in stereo if you filter it out. That's one reason why some people suggest that you need two subs, ... or full-range speakers in front.

Some NADS have a reputation for audible hum and hiss. You have to live with it. NAD is good value for the money but you get what you pay for.

I think a Centrik would be fine as a centre It's more likely to match than a different brand, if you can find one. As far as other brands go, trust your ears. Remember Linn's philosophy: "if it sounds better, it is".

So I guess in this case I have 2 options:
- Upgrade front speakers: I am thinking of the Linn Ninka (50Hz-20KHz), then set them as full range front l+r and crossover the rest of the speakers (Linn Trikan in the center and 3 Linn Unik in the back). Also the Ninka are matched to the Trikan center speaker. A bit expensive, but I will try to get them used. If I get the Ninkas I am thinking of also buying a better power amp (NAD THX 216).
- Buy a second sub (Linn Affect) - this is a cheaper option - used can be found for like $700. The only problems is that my receiver does not have l+r outs for the sub (it has only sub1 and sub2).

I am thinking that option 1 is better. Any ideas?

and regarding the center speaker - I got the Linn Trikan.