The Katana Air EX is a portable powerhouse that sounds better than the Yamaha THR30 II. It has everything that the THR is missing-a fuller sound, and creating great tones is simplistic on the Kat Air EX as the it is on the THR. Dialing in tones exactly how you want them is easy via the Boss Tone Studio on a smartphone or tablet.
I love just picking up my guitar with the wireless transmitter plugged in and it automatically turns on the Katana Air EX whenever the mood strikes without having to turn on all my gear in my studio just to play. It may cost a little more, but then again you're getting a hell of a lot more in return with the 60 Boss effects built in and stereo 5" speakers instead of 3" speakers.

Underrated and 5 stars all round being perfect out of the box without BTS. Preffered over my Katana 50 Gen3.

I would consider this a pretty expensive device, personally. But, after having done quite a bit of research, I really felt like it would it would encourage me to play guitar more. And it absolutely does! The convenience factor of the wireless system- and the fact that when you pick up your guitar the amp turns on- just makes for an awesome combo. Plenty of quality effects on tap- and the 2 x 5" speakers with the bass port really sound nice in room. It is expensive- but I won't be dropping $ each on a half dozen guitar pedals and I don't have to move a pedal board around or fiddle with wires. I play twice as much now as I did with my old rig- and control everything from my seat with the phone app. If you're a couch guitar player- this thing is the jam! Highly recommended for living room players.

I love this amp. It was perfect for what I needed. I wanted an amp for practicing and I hated having to turn everything on and hook everything up (I know, I know). This amp makes this super easy. I practice a bunch, set my guitar down, it goes to sleep and then pick it back up when I have time and it turns on right where you left off. Not really sure on battery life because I've never hit it. I have left it in sleep mode over night and it worked the next day.

Also this amp sounds really good. It's got lots of tone.

Pros:
- super convenient
- love the fact that you can do everything on the amp or in the app
- sounds really good. very loud in a "smaller" room
- love the presets; easy to switch to something you know
- runs on batteries (AAA batteries) or AC

Cons (these are pretty minor):
- a little on the heavy side
- no rechargeable battery unless you purchase the additional battery pack - separate charger as well.

I upgraded from the OG air and it was worthwhile. Sound is spatial and fills the stereo field. Easily dial in the heavies and the feels.
This is perfect for noodles and doodles of fun while watching tv

This is not something for gigging.

App works great
Never had pops or unwanted noise issues with wireless unit.

Works perfectly
I bought rechargeable batteries for the OG air five years ago and they're still running

Love the compact nature of Yamaha bluetooth amps but could never quite get over the sound coming out of 3inch speakers. The Katana EX takes care of that. 5inch speakers. Sounds awesome. Well made, solid piece of gear. Has no built-in battery or tuner, but the app is great. And unlike the Yamaha, it includes a transmitter. And the motion sensor is a game changer. Just pick up your guitar and play. Love this thing

So I tried to like this piece of gear. Paid way too much not to give it some love. First, it's over priced by a mile. The blue tooth wireless is noisy and makes popping sounds every time. I bought the Bluetooth foot pedal and there is no way to edit from the app and have the foot pedal working at the same time. For over $ all together they need that worked out. It's not! Nobody mentioned that in reviews. This thing is for a teenager with rich parents and the kid has no clue what he is doing. Real working players should just run away from this nonsense. I like Boss and own a bunch of their equipment. This is not worthy of the price for serious players. Nuff said..

Before I get into the sonics, let me say that I had a helluva time getting this amp to connect with the Boss Tone Studio (BTS) app. After some back and forth with Roland support, I got it going. Here is what I replied to Roland with:

I was finally able to get it to connect. In my opinion, the manual is not clear enough. To be specific, the manual does NOT instruct you to actually choose KATANA AIR MIDI while in the BTS app. It simply says, " 5. From your mobile device app "BOSS TONE STUDIO" initiate pairing. "

I believe that it should say, " 5. From your mobile device app "BOSS TONE STUDIO" initiate pairing by allowing the connection to KATANA AIR MIDI. "

Worse yet, directly under the instructions for this, there is a specific warning about NOT connecting to KATANA AIR MIDI. I realize now that this is ONLY intended as a warning while in a mobile device's Bluetooth settings. This warning should be moved to the section for Bluetooth Audio. It doesn't belong in the section for connecting to the BTS app.

TL;DR; While in the BTS app, you SHOULD connect to KATANA AIR MIDI! No firmware update is necessary for this "EX" model to connect to the latest BTS app.

So how does it sound with bass guitar? It sounds OK and definitely good enough for practicing. Strangely, the "Acoustic/Bass" channel does not sound good for my tastes. It is far too muffled. Use the "Clean" channel instead. There is a low-mid push when using it with bass. It would probably be awesome with fretless. All in all, it is quite fun to sit on the couch and jam along to YouTube on the living room tv with this setup. I also have a guitar and it sounds quite good to my bass-playing ears.

I was very excited to try this amp out, but upon testing it in one of their demo rooms, I realized the quality was very poor. I originally thought it might have been an issue with the wireless transmitter, but when I plugged in, the quality was just as bad. I understand that it is very hard to emulate a good distorted tone the smaller the amp gets, but for the price Boss is asking for this, I was dissapointed. I was lucky to have the 50 watt katana in the same room because it gave some context, and for a little under $300 less then the air-ex, the quality was exponentially better. It had very little feedback (air ex was very muddy and had a trebly, screechy noise whenever I muted the strings after playing), and was altogether better than the air ex in every aspect aside from portability. As an alternative, I highly recommend the yamaha thr30ii, as although it is cheaper and is less versatile than the air-ex, the tones are much fuller and actually sounds like a real amp, just a little quiter. Also if you buy it as a package deal with the line 6 gt10 wireless transmitter, it ends up only being $50 more than the air-ex, and it is worth every penny.

This unit is all about shaping sounds. I've tried two Fenders Pro and Ultra and an Ibanez Artcore Jazz with amazing sound and effects to cover many playing styles. Six of these can be saved (3 on A and 3 on B channel) as livesets and dialed up as needed. With the line out send to the front mix or stage amp/cab setup. Lots of livesets can be downloaded from Boss.

For me I wanted to shape the sounds of harmonicas and this more than fits the bill. Going wireless required a small harmonica dynamic mic, Lekato MW-1 5.8Ghz wireless mic setup (really small) and a Shure A85F matching transformer into the wired guitar input. I'm wondering if the Boss WL-30XLR mic wireless system transmitter (or others) would connect with the built-in receiver but didn't want to purchase them just to find out. Note that the wireless system and wired guitar input cannot be used at the same time. The wired guitar input disables wireless and charging the wireless transmitter in the unit disables the wired guitar input.

Bluetooth adds a lot of abilities with wireless pedals, backing tracks or just going to a party and playing tunes from a smart phone or an MP3 player connected to the Aux in. Steely Dan's Deacon Blues sounds great. Note that Bluetooth and Aux bypass the preamp and effects only available with the wireless system, wired guitar input and USB computer connections. This is as it should be when dialing in an instrument. Effects can be adjusted from the Bluetooth device.

OK, it is expensive. I get it. Then it comes with essentially the Boss WL-20L guitar wireless system built-in which isn't cheap. Add in high quality effects that other small portable practice amps rarely have. If one breaks or loses the transmitter hopefully the Boss WL-T transmitter sold separately would connect. There are no wired inputs for a pedal to switch livesets so it's an A/B button press, smart phone software or Bluetooth hardware to do this. Note Boss has not yet listed a Boss Tone Studio app for PC or Mac specifically for this unit.

It is a brand new unit so questions will eventually be answered. Overall a high quality setup in a small well built package with loud dual 5in speakers for playing anywhere. If it is easy to setup and use it is going to be used a lot!