recording to Reel to Reel directly from "preamp out"

Yes of course you can. Just remember preamp out is variable output, the volume control will affect your signal level on the deck. You can even monitor, simply connect the monitor out from the tape deck to your power amp. Just remember to not touch the volume control while doing this or you will mess up your tape level.  

I would play around to find the preamp volume setting that will allow you to adjust the tape record level using the tape deck level with the tape control somewhere around the middle of its range. Not critical but you will probably find it easier to get a good level this way. Then just remember if you do try and monitor using the power amp the signal coming off the tape deck is driving the power amp. So it is what it is in terms of volume, you will not be able to adjust it without messing with your record level.

Just remember preamp out is variable output

Good call @millercarbon. That's something very important that I had overlooked.
A question though?

Then just remember if you do try and monitor using the power amp the signal coming off the tape deck is driving the power amp.

When using the Preamp out, doesn't that take the amp out of the system? IOW disable it? I would think so, unless using Y adapters. But I cannot see any advantage to that. He should be able to moniotor it with the tape deck headphone output. What am I missing? Thanks

I'm assuming an integrated amp with pre-out also has power-in. Not necessarily but often times the way it is.  

Headphone monitor will be better as that will allow volume adjustment and not require an interconnect.

Its a 5300 Mac It has bars guys. You have to pull the bars so you loose your monitor amps. Unless you plug in headphone no way to monitor and check your playback. Kinda 101 to see if your recording is any good make your tweaks and RE record when you get it right..

I thought of something that might work split the signal where the bars ARE. You know 2 in 4 out cable. That might just work.. and still give you Tone control to both leads OUT.. Use a high quality woven jumper RCA copper/silver or pure silver or pure copper..

That will work one pair of leads back into the power amps and the other to the Reel to Reel.. Loop it back into an input.. You made a tape loop, just no button to engage it.. A hi quality A/B or both switch would work too.

Regards

For best SQ, it's better to plug the source component directly into the reel-to-reel if and when possible (if your integrated contains your RIAA phono stage, obviously not). Not convenient, but if you don't do it often not that big a deal.