You can use the [MERGE FX] knob to apply effects for mixing from the current track to the next.
Use Merge FX with rekordbox as follows:
1. Press the [MERGE FX] knob to turn on Merge FX.
　The effect set to [BUILD FX] is applied to the track, and the sample sound/oscillator sound set to [BUILD SAMPLE] starts playing.
2.Turn the [MERGE FX] knob.
　The effect set to [BUILD FX] and the sample sound/oscillator sound set to [BUILD SAMPLE] change.
3. Press the [MERGE FX] knob again to turn off Merge FX.
The Release FX set to [RELEASE FX] is applied to the track, the effect sound, and the sample sound/oscillator sound. Then, the sample sound set to [DROP SAMPLE] plays after a set amount of time.
• If [Preferences] > [Controller] > [Effect] > [MERGE FX] > [Stop playing the operating deck after MERGE FX finishes] is set, playback stops on the relevant deck.

Yes. You can change the Merge FX settings in rekordbox.
Change the Merge FX settings when your computer is connected to the DDJ-FLX6.
To turn on/off or change the settings of Merge FX without connecting the DDJ-FLX6, you’ll need to take out one of the relevant rekordbox subscription plans.
You’ll also need to mark the [Enable MERGE FX] check box in the [Preferences] > [Controller] > [Effect] tab in rekordbox.

You can change the Merge FX settings as follows:
For details, refer to [rekordbox] > [Changing the Merge FX settings] in the Instruction Manual.
You can read the Instruction Manual [here].

1. Open the [Effect] panel in rekordbox.
2. Click the gear icon shown on the right side of the [MFX] panel in the [Effect] panel to display the [MERGE FX Settings] screen.
3. Select a preset from the [PRESET] pull-down menu.
4. Select an item for [BUILD FX], [BUILD SAMPLE], [RELEASE FX], or [DROP SAMPLE] from the relevant pull-down menu.
- If you select a different preset, [CUSTOM] is displayed after the preset name.

- If you click the [RESET] button after changing a preset, the preset returns to the default.

・You need to select the sample sound when you make the following settings. Click the [?] icon to select the sample sound (you need to load the sample sound into the sampler slot before you do this).
　[BUILD SAMPLE] ＞ [REPEAT SAMPLE]
　[BUILD SAMPLE] ＞ [REPEAT UP SAMPLE]
　[DROP SAMPLE] ＞ [SAMPLER]

You can use the [MERGE FX] knob to apply effects for mixing from the current track to the next.
Use Merge FX as follows:
1. Press the [MERGE FX] knob to turn on Merge FX.
2. Turn the [MERGE FX] knob.
The effect sound changes.
3. Press the [MERGE FX] knob again.
The effect sound changes again.
4. Turn Merge FX off.
You can turn Merge FX off in any of the following ways:
• Press the [PLAY/PAUSE] button.
• Press a Performance Pad while the unit is in Hot Cue mode.
• Press the [MERGE FX] select button.
• Press the [CUE] button during cue standby.
• Touch the jog wheel.

It's not possible to customize Merge FX in Serato DJ Pro.

Turn on the [JOG CUTTER] button and you can move the jog wheel to create professional-sounding scratch effects (“scratch play”) with a section of a track.

To do this, follow the instructions below:
1. Load a track and set a Hot Cue or a cue point.
2. Press the [JOG CUTTER] button.
• If Vinyl mode isn’t turned on, turn it on before you press the [JOG CUTTER] button.
3. Hold the top of the jog wheel.
The playback position moves to the Hot Cue point or the cue point and “scratch play” starts.
4. Move the jog wheel to start “scratch play”.
Different scratch effects are assigned to 6 areas of the jog wheel.(*)
The type of “scratch play” changes as you change the scratch area by checking the indicator (Jog LED) that appears when you touch the top of the jog wheel.
*Six sections are indicated on the top surface of the jog wheel to show you the boundaries of each area.

5. Release your hand from the top of the jog wheel.
“Scratch play” stops and the track continues to play as normal from the Hot Cue/cue point.

• “Scratch play” starts from the current playback position if [Jumps to the last played HOT CUE/CUE point.] isn’t selected in [Preferences] > [Controller] > [Deck] > [JOG CUTTER].

Turn on the [JOG CUTTER] button and you can move the jog wheel to create professional-sounding scratch effects (“scratch play”) with a section of a track.

To do this, follow the instructions below:
1. Load a track and set a Hot Cue.
2. Press the [JOG CUTTER] button.
• If Vinyl mode isn’t turned on, turn it on before you press the [JOG CUTTER] button.
3. Hold the top of the jog wheel.
The playback position moves to the Hot Cue point, and “scratch play” starts.
4. Move the jog wheel to start “scratch play”.
Different scratch effects are assigned to 6 areas of the jog wheel.(*)
The type of “scratch play” changes as you change the scratch area by checking the indicator (Jog LED) that appears when you touch the top of the jog wheel.
*Six sections are indicated on the top surface of the jog wheel to show you the boundaries of each area.
5. Release your hand from the top of the jog wheel.
“Scratch play” stops and the track continues to play as normal from the Hot Cue point/playback position.

Yes. The way to do this depends on which DJ application you're using.

■rekordbox
rekordbox has a MIDI Learn feature. You can use it to change the buttons or knobs that features are assigned to. For details, see the MIDI Learn Operation Guide [here].

■Serato DJ Pro
Serato DJ Pro has a Remapping feature. You can use it to change the buttons or knobs that features are assigned to. For details, see the Serato DJ Pro software manual on the Serato website [here].

Yes.
For details, refer to the Instruction Manual > [Changing the settings] > [Utilities mode].
You can read the Instruction Manual [here].

The buffer size setting is a detailed setting related to audio transmission.
When you hear sound cuts or delays in operation, you can solve the issue by adjusting the buffer size. The larger the value of [Sample], the less likely you’ll hear sound cuts etc. The smaller the value is, the less likely you’ll experience delays in operation.

If you experience issues such as sound cuts, set the buffer size to a large value such as 1024 samples. Next, play a track and check it no longer cuts out. Then, change to a low value and use the unit. Repeat these steps until the sound cuts stop and you don't experience a delay in operation.

The process for adjusting buffer size depends on which DJ application you use.

■rekordbox
Adjust buffer size in rekordbox [Preferences] > [Audio] > [Buffer size].
(Windows users, click [Setting Utility] in the same window and adjust it on the [ASIO] tab.)

■Serato DJ Pro
Adjust buffer size in Serato DJ Pro [Setup] > [Audio] > [USB buffer size].

*The best value to set depends on your system specification.
*You don’t need to adjust buffer size if you’re not experiencing a particular problem.

Yes.
You can change the PC/Mac sound setting so you won’t hear the error sound.

■ Windows
Go to [Control Panel] > [Sound] > [Program Events] and turn off all sound settings.

■ Mac
Open System Preferences > Sound Panel > Sound Effects and change the device to something other than the DDJ-FLX6.

After your PC/Mac returns from standby or sleep mode, be sure to reconnect the unit and restart your DJ application before using it.
We don’t guarantee stable operation when your PC/Mac has recovered from standby or sleep mode.

See the MIDI message list [here].