Bellari 129 or phono imput on my onkyo pre/pro

I am just getting my feet wet with vinyl and i have the following question...

I just bought a shiny new pro-ject rm 1.3 and will be setting it up in my theater. I have magnepans 1.7's as mains and my onkyo pr/sc 886 pre/pro has a phono imput...and now for the question...

Would i be better off with the bellari 129 tube phono preamp or the phono imput in the onkyo?

Thanks in advance,
My guess is the bellari, but the onkyo might surprise. Listen to the pre you have for while and if you feel the sound is overly dry or something is missing, add the tubes later.
why is the Belari your only external phono option? IMO there are many other budget phono stages that are better, or at least worth considering.

Either way, I'd try/use the Onkyo stage until I decided it wasn't doing the job, then upgrade to an external stage.
I chose the bellari because it is a tube which i thought might pair well with the maggies...also it is inexpensive and is well reviewed...other than that im open to suggestion.
You need to listen to decide. Fortunately, the Bellari, and several other budget phono preamps, are available from mail-order sellers that offer good return policies. Try a comparison between some of these preamps and the built-in preamp on your Onkyo. Then decide if any improvements are worth the investment. Don't forget to figure a decent pair of interconnects into the equation of an outboard phono preamp.
I'm not sure what the Bellari is selling for now, but I had one some time ago when the price was $129. At that price it was ok, but there are problems with it. It may be a good choice for you, but realize not everyone had a good experience with it. If the price is still up in the $175 range, a far better choice at that price point IMO is a Musical Fidelity XLP which can be found for $165 /-.