Will the sound quality deminish over the years?

"11-09-14: Phasecorrect
Hate to be a buzzkill...but FM frequency cuts out @ 15 kHz...so the improvements attributed to the Nad are largely imaginative...that said, its a very good tuner."

"11-10-14: Mceljo
Nonoise - I like how your perspective shifted from the Marantz lacking the highs to it adding mid and bass. The change in perspective caused you to no longer think of it as not sounding as good as the NAD. Now that your assumption has changed for the Marantz, you will likely enjoy it rather than wish it sounded like the NAD. You may still prefer the NAD, but I am fascinated by how our brains work."

Why the assumption that the change is imagined? That's pretty far fetched. He listened to the NAD tuner on a regular basis for over 20 years. I think its far more likely his guess that the extension in the HF's are too blame is wrong, and that there is some other real cause for the difference between the 2 tuners.

"11-10-14: Mceljo
Zd542 - I didn't suggest that the change wasn't real. I did, however suggest that when his perspective changed he no longer viewed the Marantz as lacking highs, but rather have a more full mid and bass range. The sound of the Marantz was constant, but his assumption about it changed resulting in a different experience."

I think you may be right. Reading Nonoise's posts, I thought he was kidding. Reading them again, I'm not so shure. If he was being serious, I agree with you.