diff --git a/pkg/rtc/mediatracksubscriptions.go b/pkg/rtc/mediatracksubscriptions.go
index 8ab9b5ed5..145d8cc59 100644
--- a/pkg/rtc/mediatracksubscriptions.go
+++ b/pkg/rtc/mediatracksubscriptions.go
@@ -103,7 +103,7 @@ func (t *MediaTrackSubscriptions) AddSubscriber(sub types.LocalParticipant, wr *
 		t.subscribedTracksMu.Unlock()
 		sub.VerifySubscribeParticipantInfo(subTrack.PublisherID(), subTrack.PublisherVersion())
 		sub.AddMuxAudioTrack(subTrack.PublisherID(), trackID, wr)
-		return nil
+		return subTrack, nil
 	}
 
 	var rtcpFeedback []webrtc.RTCPFeedback
diff --git a/pkg/rtc/participant.go b/pkg/rtc/participant.go
index 6a795ec26..51bca7c9a 100644
--- a/pkg/rtc/participant.go
+++ b/pkg/rtc/participant.go
@@ -844,8 +844,9 @@ func (p *ParticipantImpl) GetConnectionQuality() *livekit.ConnectionQualityInfo
 
 	subscribedTracks := p.SubscriptionManager.GetSubscribedTracks()
 	subscriberScores := make(map[livekit.TrackID]float32, len(subscribedTracks))
+	// TODO-mux: calculate score for muxed tracks
 	for _, subTrack := range subscribedTracks {
-		if subTrack.IsMuted() || subTrack.MediaTrack().IsMuted() {
+		if subTrack.IsMuted() || subTrack.MediaTrack().IsMuted() || subTrack.DownTrack() == nil {
 			continue
 		}
 		score := subTrack.DownTrack().GetConnectionScore()
@@ -1286,10 +1287,18 @@ func (p *ParticipantImpl) subscriberRTCPWorker() {
 		var srs []rtcp.Packet
 		var sd []rtcp.SourceDescriptionChunk
 		subscribedTracks := p.SubscriptionManager.GetSubscribedTracks()
+		downtracks := p.audioForwarder.GetDowntracks()
 		p.lock.RLock()
 		for _, subTrack := range subscribedTracks {
-			sr := subTrack.DownTrack().CreateSenderReport()
-			chunks := subTrack.DownTrack().CreateSourceDescriptionChunks()
+			if subTrack.DownTrack() == nil {
+				continue
+			}
+			downtracks = append(downtracks, subTrack.DownTrack())
+		}
+
+		for _, dt := range downtracks {
+			sr := dt.CreateSenderReport()
+			chunks := dt.CreateSourceDescriptionChunks()
 			if sr == nil || chunks == nil {
 				continue
 			}
@@ -2133,7 +2142,7 @@ func (p *ParticipantImpl) addDowntrack() error {
 	// })
 
 	// Bind callback can happen from replaceTrack, so set it up early
-	downTrack.OnBind(func() {
+	downTrack.OnBinding(func() {
 		p.audioForwarder.AddDownTrack(downTrack)
 		// wr.DetermineReceiver(downTrack.Codec())
 		// if reusingTransceiver.Load() {
@@ -2158,7 +2167,7 @@ func (p *ParticipantImpl) addDowntrack() error {
 	})
 
 	downTrack.OnRttUpdate(func(_ *sfu.DownTrack, rtt uint32) {
-		go p.UpdateRTT(rtt)
+		go p.UpdateMediaRTT(rtt)
 	})
 
 	downTrack.AddReceiverReportListener(func(dt *sfu.DownTrack, report *rtcp.ReceiverReport) {
diff --git a/pkg/rtc/subscribedtrack.go b/pkg/rtc/subscribedtrack.go
index 3a08c731f..c3e6cee92 100644
--- a/pkg/rtc/subscribedtrack.go
+++ b/pkg/rtc/subscribedtrack.go
@@ -51,7 +51,7 @@ func NewSubscribedTrack(params SubscribedTrackParams) *SubscribedTrack {
 	s := &SubscribedTrack{
 		params: params,
 		logger: params.Subscriber.GetLogger().WithValues(
-			"trackID", params.DownTrack.ID(),
+			"trackID", params.MediaTrack.ID(),
 			"publisherID", params.PublisherID,
 			"publisher", params.PublisherIdentity,
 		),
diff --git a/pkg/sfu/audioselection/forwarder.go b/pkg/sfu/audioselection/forwarder.go
index 5a684623e..d3a7f5212 100644
--- a/pkg/sfu/audioselection/forwarder.go
+++ b/pkg/sfu/audioselection/forwarder.go
@@ -90,9 +90,18 @@ func (f *SelectionForwarder) AddDownTrack(dt *sfu.DownTrack) {
 	f.lock.Unlock()
 }
 
+// TODO-mux: impelement
 func (f *SelectionForwarder) RemoveDownTrack(dt *sfu.DownTrack) {
 }
 
+func (f *SelectionForwarder) GetDowntracks() []*sfu.DownTrack {
+	f.lock.RLock()
+	defer f.lock.RUnlock()
+	tracks := make([]*sfu.DownTrack, len(f.downtracks))
+	copy(tracks, f.downtracks)
+	return tracks
+}
+
 // OnForwardMappingChanged is called when the forward mapping is changed, used to update the relationship between downtracks and sources
 func (f *SelectionForwarder) OnForwardMappingChanged(h func(muxInfo []*livekit.AudioTrackMuxInfo)) {
 	f.onForwardMappingChanged = h
diff --git a/pkg/sfu/audioselection/nullreceiver.go b/pkg/sfu/audioselection/nullreceiver.go
index 24c1e7520..2f6e3ed18 100644
--- a/pkg/sfu/audioselection/nullreceiver.go
+++ b/pkg/sfu/audioselection/nullreceiver.go
@@ -4,6 +4,7 @@ import (
 	"github.com/pion/webrtc/v3"
 
 	"github.com/livekit/livekit-server/pkg/sfu"
+	"github.com/livekit/livekit-server/pkg/sfu/buffer"
 	"github.com/livekit/protocol/livekit"
 )
 
@@ -35,8 +36,8 @@ func (r *NullReceiver) HeaderExtensions() []webrtc.RTPHeaderExtensionParameter {
 func (r *NullReceiver) ReadRTP(buf []byte, layer uint8, sn uint16) (int, error) {
 	return 0, nil
 }
-func (r *NullReceiver) GetLayeredBitrate() sfu.Bitrates {
-	return sfu.Bitrates{}
+func (r *NullReceiver) GetLayeredBitrate() ([]int32, sfu.Bitrates) {
+	return nil, sfu.Bitrates{}
 }
 func (r *NullReceiver) GetAudioLevel() (smooth, loudest float64, active bool) {
 	return 0, 0, false
@@ -70,3 +71,11 @@ func (r *NullReceiver) GetRedReceiver() sfu.TrackReceiver {
 func (r *NullReceiver) GetTemporalLayerFpsForSpatial(layer int32) []float32 {
 	return nil
 }
+
+func (r *NullReceiver) GetRTCPSenderReportDataExt(layer int32) *buffer.RTCPSenderReportDataExt {
+	return nil
+}
+
+func (r *NullReceiver) GetReferenceLayerRTPTimestamp(ts uint32, layer int32, referenceLayer int32) (uint32, error) {
+	return ts, nil
+}
diff --git a/pkg/sfu/downtrack.go b/pkg/sfu/downtrack.go
index 4f7ef920e..ea3d96250 100644
--- a/pkg/sfu/downtrack.go
+++ b/pkg/sfu/downtrack.go
@@ -259,7 +259,9 @@ func NewDownTrack(
 	d.receiverLock.Lock()
 	d.receiver = r
 	d.receiverLock.Unlock()
-	d.forwarder = NewForwarder(d.kind, d.logger, d.receiver.GetReferenceLayerRTPTimestamp)
+	d.forwarder = NewForwarder(d.kind, d.logger, func(ts uint32, layer, referenceLayer int32) (uint32, error) {
+		return d.getReceiver().GetReferenceLayerRTPTimestamp(ts, layer, referenceLayer)
+	})
 	d.forwarder.OnParkedLayersExpired(func() {
 		if d.onSubscriptionChanged != nil {
 			d.onSubscriptionChanged(d)