tape cal is pretty much I like chocolate/I like vanilla stuff.
Do you know how to cal the deck with confidence? If so, here's my advice:
Record what you normally record while playing around with the hi/lo eq and the bias. When you find the sound that you like, go and cal the machine to spec and make a note of how far off you were... The most righteous kick drum sounds come from a track biased in a way that would make your vocals sound like garbage... You can get very creative with your calibration and if you are doing everything in house it totally doesnt matter at all. If you are going 9dB over bias, that could be some trouble for the machine down the line, but if you know what you are doing, cal'ing the deck so that not every track is totally flat can be used to your advantage. Low freq head bump is your friend, figure out how to use it.
If you dont know how to cal the deck, forget EVERYTHING I just said, you want to just get everything to spec and even and have a party without making a total mess...
All that said, you'll find a level that works for you, depending on what you record. Ive told people in the past online who have asked about what level to cal their deck to and suggested that they just listen and people have had F*cking caniptions over that advice, but it really is the best advice. I recorded on a standard cal for years before I came to the conclusion that I didnt like it as I never LISTENED to what it actually did to the tape, I just figured you had to do it that way or Lanoz the god of sound would materialize on earth and shoot lightning bolts out of your erase head at you...
If you dont know where to start, Q456 @ +6/185 nW/m is a sound that is pretty standard all over the world. Depending on the integrity of the electronics of your deck you could try it at +9 if you have the bias to get up that high. The tascam probably wont, I had an MSR-16 and +6 was all it had in it on a good day... Check out GP9 @ +6/185. Its a +9 stock but I dont like it at +9 at all. You might love it... It's totally chocolate vanilla kind of stuff. Forget what the tape wants (manufacturer spec and all that) and focus on what your specific machine can deliver for you with that tape. Sort of like a porcshe with a professional driver vs. porsche with me driving... Same car, same factory spec, totally different performance...
When it comes to the level you are gonna be working at, its really specific to the electronics in your specific deck, I dont care what anyone says about that, and believe me, Ive caught hell for suggesting such a blasphemous idea that +6 on my Sh*tty antique deck with rotting electronics sounds different than +6 on a different deck, etc... Listen to what your machine wants to do, there's probably a window where you'll find what sounds REALLY good to you. I have a new tape machine and spent three 12 hour days calibrating it this week. Thats a really long time to sit on the floor turning tiny screws... If you put the time in, you can solve a lot of problems if you custom tailor your calibration, but maybe thats a bit beyond what you are asking, I dont know. The most important thing is to listen to what the deck is doing, just because some cal is cool on this machine dont mean its cool on another.
My favorite story is the day I believed the hype about +9 for rock (for classical, sure) and brought an MM1100 up to +9, recorded kick and snare in my usual fashion and then proceeded to replace a handful of diodes on the record and playback cards that the drum tracks were recorded on. This was around the time whe GP9 first came out and everyone was wearing those quantegy shirts with the needle bending on the VU and some slogan like "push it to the pins" or something like that, cant remember exactly.
too much info maybe...
Just remember, for everyone telling you how end all be all a certain level is, the first handful of Led Zeppelin records were recorded at 185. Thats ZERO. If you can put balls like that on a tape at plus zero nW/m, that whole debate about level can more or less kiss my ass...
dave