First things first: Jimmy Fallon’s second album is not necessarily a standalone comedy album. It’s essentially a soundtrack to Fallon’s wildly popular water-cooler-moment factory late-night talk show, collecting some of his more inspired musical bits, lifting them directly from the show (enthusiastic crowd reaction and all), and compiling them one convenient platter. Depending on your take on Fallon’s career, this could be a good or a bad thing; after all, as a “Saturday Night Live” cast member, he released his first record, 2002’s The Bathroom Wall, to a collective shrug.

Then again, Fallon was a younger comedian back then, perfectly happy to throw everything at the (bathroom) wall and just see what sticks. The Jimmy Fallon of 2012 has widespread appreciation on his side, with plenty of former detractors coming out of the woodwork to give a big ole thumbs-up to his buoyant, novel, music-geek approach to “Late Night”; his boyish enthusiasm still shines through, but he’s upped his professionalism and confidence considerably since the “SNL” days. Blow Your Pants Off collects many of the moments this heightened comic sensibility – and lucrative partnership with Best Band In The World (TM) The Roots – has yielded, but does the comedy translate in purely audio form?

The answer: eh, kinda. Don’t get me wrong; most of these are stellar bits. The recurring concept of Fallon impersonating legendary musicians singing vintage television themes almost always works, and the crackerjack “Slow Jam the News” segments are always, always gold. But they benefit largely from the element of surprise; when Jimmy as Neil Young covers “Whip My Hair”, it’s funny, but it reaches nirvana when Bruce Springsteen, dressed as his Born to Run-era younger self, steps out of the shadows to turn it into a duet. There’s a visual element to these songs, and it’s somewhat lost in translation when NBC.com and Hulu still host most of these bits; one could theoretically say the same thing about an artist like The Lonely Island, but their outlandish Turtleneck & Chain was such an accurate facsimile of modern pop music that the songs boast legitimate replay value, not to mention jokes that go beyond the premise. On Blow Your Pants Off, the jokes generally are the premise – “and now, I’ll be playing Jim Morrison, singing a song that The Doors would not in all likelihood have performed” – and there’s nothing wrong with that; these are quick late-night talk show comedy bits, after all, and shouldn’t be faulted for their brevity or their single-joke concept. Still, it’s difficult to imagine listening to often; those familiar with the show will have already memorized every comedic beat, while non-fans aren’t likely to get the charm of these bits from merely hearing them.

That said, Fallon is certainly a gifted man; as a mimic, he’s almost unparalleled, able to capture Neil Young’s fragile tenor, Jim Morrison’s full-throated slur, and David Bowie’s quivering baritone with equal ease. Without the benefit of video, we’re able to hear how well Fallon commits to the impersonations; making him up to look like the performer in question is easy, but Jimmy isolates and captures every vocal tic stunningly. And The Roots are perfect foils; they’re arguably the most diverse band in the popular lexicon these days (a fact easily illustrated by listening to any of their genre-spanning studio records), but “Late Night” has also betrayed a breezy sense of fun and an anything-goes gamesmanship that their super-serious albums don’t.  And they back up Fallon at every turn, recreating the ominous keyboard trills and pinging guitars of The Doors in “The Doors Sing ‘Reading Rainbow'”, stripping down to classic-punk roots on Ramones pastiche “My Upstairs Neighbors Are Having Sex (And Listening to The Black Eyed Peas)”, and lathering on a layer of thick, buttery Teddy Pendergrass soul for “Slow Jam the News”.

When these two factors – Fallon and The Roots – dovetail at the same time, the results can be lovely; the oft-viewed “History Of Rap” medley finds Fallon and guest Justin Timberlake trading stellar rapper impressions over The Roots’ vise-tight rhythms. Questo and crew accurately recreate “Rapper’s Delight”, “Live Your Life”, “Juicy”, and more live, switching songs on a dime, never faltering. They provide a massive vocal counterpoint to a vamping Fallon and Eddie Vedder on the uproarious, insidiously catchy “Balls In Your Mouth”. They even transform Rebecca Black’s notorious “Friday” into a sweeping, dramatic rock anthem (with the help of a stone-faced Stephen Colbert).

So, while Blow Your Pants Off is fun, the reaction it actually inspires is “hey, this is a fun clip. I should check it out on Hulu.” This seems counter-productive for a platter billed as a comedy album; there’s no denying Fallon’s versatility or skill as a performer, and the sheer enthusiasm with which he performs his job is both laudable and endearing, but taken as a strictly auditory experience, Blow Your Pants Off is underwhelming. “Late Night” hits it out of the park night after night; as for Jimmy Fallon, the recording artist, consider my pants still on.

Well, okay, that part’s a lie, but they weren’t blown off, is the point.

Enjoy that image, America.

Grade: C+