diff --git a/api/relay.go b/api/relay.go
index b07204b9..5d93b358 100644
--- a/api/relay.go
+++ b/api/relay.go
@@ -11,6 +11,7 @@ import (
 	"api.audius.co/trashid"
 	"connectrpc.com/connect"
 	v1 "github.com/OpenAudio/go-openaudio/pkg/api/core/v1"
+	"github.com/OpenAudio/go-openaudio/pkg/sdk"
 	cconfig "github.com/OpenAudio/go-openaudio/pkg/core/config"
 	"github.com/OpenAudio/go-openaudio/pkg/core/server"
 	eth_gen "github.com/OpenAudio/go-openaudio/pkg/eth/contracts/gen"
@@ -259,37 +260,43 @@ func (app *ApiServer) relay(c *fiber.Ctx) error {
 	})
 }
 
+const sosEndpoint = "https://sos.audius.co"
+
 func (app *ApiServer) handleRelay(ctx context.Context, logger *zap.Logger, decodedTx *v1.ManageEntityLegacy) (*v1.Transaction, error) {
-	allClients := app.openAudioPool.GetAll()
-	if len(allClients) == 0 {
-		logger.Error("no OpenAudio clients configured")
-		return nil, fmt.Errorf("no OpenAudio clients configured")
-	}
-
-	var lastErr error
-	for i, clientInfo := range allClients {
-		endpointLogger := logger.With(zap.String("openaudio_endpoint", clientInfo.Endpoint), zap.Int("attempt", i+1))
-		res, err := clientInfo.Client.Core.SendTransaction(ctx, connect.NewRequest(&v1.SendTransactionRequest{
-			Transaction: &v1.SignedTransaction{
-				Transaction: &v1.SignedTransaction_ManageEntity{
-					ManageEntity: decodedTx,
-				},
+	req := &v1.SendTransactionRequest{
+		Transaction: &v1.SignedTransaction{
+			Transaction: &v1.SignedTransaction_ManageEntity{
+				ManageEntity: decodedTx,
 			},
-		}))
-
-		if err != nil {
-			lastErr = err
-			endpointLogger.Warn("transaction failed, trying next", zap.Error(err))
-			continue
+		},
+	}
+
+	// mainnet
+	go func() {
+		allClients := app.openAudioPool.GetAll()
+		for i, clientInfo := range allClients {
+			endpointLogger := logger.With(zap.String("openaudio_endpoint", clientInfo.Endpoint), zap.Int("attempt", i+1))
+			res, err := clientInfo.Client.Core.SendTransaction(context.Background(), connect.NewRequest(req))
+			if err != nil {
+				endpointLogger.Warn("transaction failed, trying next", zap.Error(err))
+				continue
+			}
+			endpointLogger.Info("transaction confirmed", zap.String("hash", res.Msg.Transaction.GetHash()))
+			return
 		}
+		logger.Error("all mainnet endpoints failed")
+	}()
 
-		msg := res.Msg.Transaction
-		endpointLogger.Info("transaction confirmed", zap.String("hash", msg.GetHash()))
-		return msg, nil
+	// sos
+	sosClient := sdk.NewOpenAudioSDK(sosEndpoint)
+	sosLogger := logger.With(zap.String("openaudio_endpoint", sosEndpoint))
+	res, err := sosClient.Core.SendTransaction(ctx, connect.NewRequest(req))
+	if err != nil {
+		sosLogger.Warn("sos dual-write failed", zap.Error(err))
+		return nil, err
 	}
-
-	logger.Error("all OpenAudio endpoints failed", zap.Error(lastErr))
-	return nil, fmt.Errorf("all endpoints failed, last error: %w", lastErr)
+	sosLogger.Info("sos dual-write confirmed", zap.String("hash", res.Msg.Transaction.GetHash()))
+	return res.Msg.Transaction, nil
 }
 
 func transactionToReceipt(tx *v1.Transaction, wallet string) map[string]interface{} {