phono stage upgrade from Denon pre-amp

Look at the PRO-JECT phono stages. They have 2 tube and two transistor ones. The Tube Box 11 SE has outperformed ones costing many times more at $699. It would be a very big step up. The cheaper ones are all good in their price range. The Denon 110 is quite good. I got mine new on eBay from Yogi for $110. I would say that in the PRO-JECT line the middle two would also give a good increase in performance.

Bottlehead seduction. I ran a dl-110 thru mine for a while, good match.
I have heard good things about the Project, never heard it, but the bottlehead has quite a dedicated following, and is very tweak-able.
You can usually find them used for around $300.

I'll leave it to others to recommend phono preamps for you -- most of the ones I have heard or know about are in the $1500 to $3000+ range. What I will comment on, however, is your remark about having to turn the volume knob up to or past the 12:00 position. Is this a concern for you? If so, you might think about how the volume knob works. Essentially, it is a potentiometer/attenuator. At the full "open" position (i.e., turned fully clockwise), there is essentially no attenuation of the output signal to the amp. Conversely, when the volume is turned all the way down (fully counter-clockwise), all of the stages in the potentiometer are "in line" to reduce the signal output. Understood from this perspective, having the volume control turned up to 1:00 or 2:00 is indicative of a better-designed volume control function (greater range of movement, which enables subtler adjustments to volume). Far too many preamps / receivers have their volume knobs set to play loudly in the 10:00 to 12:00 position, which means that you have a much reduced range of rotation for the volume knob. Unless you have concerns about the QUALITY of the sound from your pre-amp, you don't need to worry about setting the volume knob above 12:00.