I don't think you can go wrong starting with a SEX amp. In its stock form, it won't have the low frequency extension or control that a Paramount has, but you will get a very different presentation of your music compared to the Denon. Also, your speakers are sufficiently sensitive that you probably should not consider any DHT (45, 2A3, 300B, etc) amp that have AC on the filaments, as hum will likely be audible.
If you can scrounge the cash, 300B Paramounts will really do what you're looking for, but the SEX amp is a good stepping stone with solid resale value in case you wish to upgrade.
-PB