As with everything, there is an App for that, and some of the Apps are very good. The sound quality of the guitar in Garage Band or the Piano in the Korg Module are light years beyond anything that was available 20 years ago and can be run on a iPhone 4.
On the downside Apple seems to have this market cornered. I looked at some of the highest rated Android apps and can't recommend any of them. After some research it seems that when Apple created the IOS they integrated audio and MIDI much better and made developer tools that could access them. Called CoreAudio and CoreMidi these let developers integrate far better.
A note about Bluetooth and latency . I have the Korg microKEY2 Air - 37. It has Bluetooth and works wirelessly without issue. Remember if you get a keyboard that connects via a USB cable, some use the USB for power as well and phones and tablets will not be able to supply that much power.
The obvious pairing with a phone app and small digital keyboard should be a Bluetooth speaker to play everything on. Unfortunately the most current version of Bluetooth in 2020 is version 5 and it still has very bad lag. I would say that it's about a half second between hitting a key on the keyboard and hearing the sound from the speaker. Just enough to make it almost impossible to play. Unfortunately there are no indications of a version 6 or addressing this issue in the near future.
Android has one last problem with Bluetooth. The problem being that it does not work natively and you need a separate Bluetooth to MIDI app. If you connect with the phones built in Bluetooth connection settings, it will not work.
- GarageBand for (iPad/iPhone)
- Korg Module Le (iPad/iPhone)
- KORG Gadget 2 Le (iPad/iPhone)
- MIDI Bluetooth (Android)
- Mini Piano Light (Android)
- Perfect Piano (Android)
- Piano MIDI (Android)
- Rockrelay Synth (Android)
- All the Rest
1. GarageBand for iOS
Sound Quality 5/5
If you have an iPad, it's a no brainer. Get Garage Band. Done. There is absolutely nothing even in the same league. As of the writing of this they reduced the cost from $6 to Free.
Not only does this have incredible piano and guitar sounds, but it includes a full music sequencer so that you can compose and arrange your own songs.
Heck, its features have features. Every time I think I've found everything this can do, I find more.
2. Korg Module Le (iPad/iPhone)
Sound Quality: 5/5
Compared to the Apple Rock band the Korg Module Le is a one trick pony. It will play one instrument at a time, no sequencer or additional feature. But wow, the piano is a work of art with the best sounding piano of any app. Another no brainer if you have an IOS device. This piano is incredible.
Korg Module LE (Free)
Korg Module Pro ($40)
The free KORG Module Le is now KORG Module.
The "LE" version is free and comes with only the one piano instrument. If you have a Korg microkey keyboard it will automatically unlock 4 more instruments (Electric Piano, Organ, Clav, and Strings).
Tip: Change the key sensitivity! The default sucks.
3. KORG Gadget 2 Le (iPad/iPhone)
Formerly the "KORG Gadget Le"
Sound Quality: 5/5
3 instruments for free, 5 if you are using a KORG keyboard. The full version of the software is $40 and includes 23 instruments.
The gem in this group is the Marseille Synth. It comes with 128 sounds and the majority of them are great. Not the best for keyboard but great synth sounds.
1. MIDI Bluetooth (Android)
If you have a Bluetooth Keyboard and an Android phone, you are going to need this. I have no idea why it "just works" on the Apple IOS, but on Android, it does not. Use this program to connect to the keyboard. Do NOT connect via Bluetooth with the standard phone settings.
2. Mini Piano Light (Android)
Sound Quality: 4/5
The piano sound of the free "Bosendorfer Imperial 290" is a solid 4/5. All of the other sounds are more of a 2/5.
3. Synth FM by Rockrelay (Android)
Sound Quality: 4/5*
This is more for FM synthesis sounds and it does those very well. If you are looking for a good sounding piano, this is not it. It does have a pleasant electric piano sound.
4. Perfect Piano (Android)
Sound Quality: 3/5
Too much reverb, and poor velocity sensitivity. It only comes with a few instruments but you can "unlock" more after watching an advertisement. The reverb does have an ON or OFF setting, but it's really a too much or nothing kind of choice.
5. Piano MIDI (Android)
Sound Quality: 3/5
Too much reverb and the Grand is not very Grand. A few free instruments, then you have to watch adds to unlock more. This would not be too bad except that it forgets what you unlocked each time you start the app.
6. All the Rest (Android)
I'm just going to give these a one liner, because I really can't recommend any of them. Either marred by horribly intrusive advertisements, poor sound quality or both. Also a bunch will not work with the Bluetooth keyboard I own.
iGrand - Simply crashes
My Piano - Will not work with my keyboard
ORG 2020 - Will not work with my keyboard
Piano Keyboard - Will not work with my keyboard
Piano Classic - Death by Adds, horrible sound
Best Piano Keyboard 2020 - Death by sustain peddle
Piano + - One piano sound included, and it is very tinny sounding