diff --git a/ktmidi-ci-tool/src/commonMain/kotlin/dev/atsushieno/ktmidi/citool/MidiDeviceManager.kt b/ktmidi-ci-tool/src/commonMain/kotlin/dev/atsushieno/ktmidi/citool/MidiDeviceManager.kt
index 995b32f3b..ec179ce89 100644
--- a/ktmidi-ci-tool/src/commonMain/kotlin/dev/atsushieno/ktmidi/citool/MidiDeviceManager.kt
+++ b/ktmidi-ci-tool/src/commonMain/kotlin/dev/atsushieno/ktmidi/citool/MidiDeviceManager.kt
@@ -24,14 +24,14 @@ class MidiDeviceManager {
                 applicationName = "KtMidi-CI-Tool V-In",
                 portName = "KtMidi-CI-Tool Virtual Out Port",
                 version = "1.0",
-                midiProtocol = MidiTransportProtocol.MIDI1, // if applicable
+                midiProtocol = MidiTransportProtocol.MIDI1,
             )
             val pcIn = PortCreatorContext(
                 manufacturer = "KtMidi project",
                 applicationName = "KtMidi-CI-Tool V-Out",
                 portName = "KtMidi-CI-Tool Virtual In Port",
                 version = "1.0",
-                midiProtocol = MidiTransportProtocol.MIDI1, // if applicable
+                midiProtocol = MidiTransportProtocol.MIDI1,
             )
 
             virtualMidiInput = midiAccessValue.createVirtualOutputReceiver(pcOut)
@@ -46,16 +46,14 @@ class MidiDeviceManager {
                 applicationName = "KtMidi-CI-Tool UMP V-In",
                 portName = "KtMidi-CI-Tool UMP Virtual Out Port",
                 version = "1.0",
-                midiProtocol = MidiTransportProtocol.UMP, // if applicable
-                umpGroup = 1
+                midiProtocol = MidiTransportProtocol.UMP,
             )
             val pcIn2 = PortCreatorContext(
                 manufacturer = "KtMidi project",
                 applicationName = "KtMidi-CI-Tool UMP V-Out",
                 portName = "KtMidi-CI-Tool UMP Virtual In Port",
                 version = "1.0",
-                midiProtocol = MidiTransportProtocol.UMP, // if applicable
-                umpGroup = 2
+                midiProtocol = MidiTransportProtocol.UMP,
             )
 
             virtualMidiInput2 = midiAccessValue.createVirtualOutputReceiver(pcOut2)
diff --git a/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/alsakt/AlsaSequencer.kt b/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/alsakt/AlsaSequencer.kt
index 9269c810c..79656d534 100644
--- a/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/alsakt/AlsaSequencer.kt
+++ b/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/alsakt/AlsaSequencer.kt
@@ -228,7 +228,9 @@ class AlsaSequencer(
     private fun sendMidi1(port: Int, data: ByteArray, index: Int, count: Int) {
         if (midiEventParserOutput == null) {
             val ptr = snd_midi_event_t()
-            Alsa.snd_midi_event_new(midiEventBufferSize, ptr)
+            val ret = Alsa.snd_midi_event_new(midiEventBufferSize, ptr)
+            if (ret < 0)
+                throw AlsaException(ret.toInt())
             midiEventParserOutput = ptr
         }
 
@@ -247,7 +249,9 @@ class AlsaSequencer(
                 eventBufferOutput.put(seq_evt_off_dest_port, AddressUnknown.toByte())
                 eventBufferOutput.put(seq_evt_off_queue, QueueDirect.toByte())
                 // FIXME: should we provide error handler and catch it?
-                Alsa.snd_seq_event_output_direct(seq, ev)
+                val ret = Alsa.snd_seq_event_output_direct(seq, ev)
+                if (ret < 0)
+                    throw AlsaException(ret)
             }
             i += ret.toInt()
         }
diff --git a/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/ktmidi/AlsaMidiAccess.kt b/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/ktmidi/AlsaMidiAccess.kt
index 0623a01e7..57c195998 100644
--- a/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/ktmidi/AlsaMidiAccess.kt
+++ b/ktmidi-jvm-desktop/src/jvmMain/kotlin/dev/atsushieno/ktmidi/AlsaMidiAccess.kt
@@ -1,7 +1,6 @@
 package dev.atsushieno.ktmidi
 
 import dev.atsushieno.alsakt.*
-import kotlinx.coroutines.delay
 
 internal fun Byte.toUnsigned() : Int = if (this < 0) this + 0x100 else this.toInt()
 
@@ -107,9 +106,12 @@ class AlsaMidiAccess : MidiAccess() {
         return AlsaMidiOutput (seq, AlsaMidiPortDetails (appPort), destPort)
     }
 
-    private val seq: AlsaSequencer by lazy { AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking) }
+    private val seqIn1: AlsaSequencer by lazy { AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking) }
+    private val seqIn2: AlsaSequencer by lazy { AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking) }
 
     override suspend fun createVirtualInputSender ( context: PortCreatorContext) : MidiOutput {
+        val seq = if (context.midiProtocol == MidiTransportProtocol.UMP) seqIn2 else seqIn1
+
         val isUmp = context.midiProtocol == MidiTransportProtocol.UMP
         val portCap = virtual_input_sender_connected_cap or
                 if (isUmp) AlsaPortCapabilities.UmpEndpoint else 0
@@ -133,7 +135,12 @@ class AlsaMidiAccess : MidiAccess() {
         return AlsaVirtualMidiOutput (seq, details, { seq.deleteSimplePort(portNumber) }, send)
     }
 
+    // should we have this as a property? It seems to cause internal crash.
+    private val seqOut1: AlsaSequencer by lazy { AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking) }
+    private val seqOut2: AlsaSequencer by lazy { AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking) }
+
     override suspend fun createVirtualOutputReceiver ( context:PortCreatorContext): MidiInput {
+        //val seq = if (context.midiProtocol == MidiTransportProtocol.UMP) seqOut2 else seqOut1
         val seq = AlsaSequencer (AlsaIOType.Duplex, AlsaIOMode.NonBlocking)
 
         val portCap = virtual_output_receiver_connected_cap or